Highest Recorded Serum Creatinine – PMC

• Journal List
• Case Rep Nephrol
• v.2021; 2021
• PMC8531789

As a library, NLM provides access to scientific literature. Inclusion in an NLM database does not imply endorsement of, or agreement with,
the contents by NLM or the National Institutes of Health.

Learn more about our disclaimer.

Case Rep Nephrol. 2021; 2021: 6048919.

Published online 2021 Oct 14. doi: 10.1155/2021/6048919

,
¹
,
²
,
¹
,
¹
,
¹
and
¹

Author information Article notes Copyright and License information Disclaimer

Serum creatinine is a commonly used laboratory marker to assess kidney function; however, there has not been an established level of serum creatinine to predict mortality. After extensive literature review, we present a case of the highest recorded serum creatinine of 73.8 mg/dL in a 23-year-old male with the history of pediatric deceased donor kidney transplant (DDKT). He initially presented with uremia and signs of acute renal allograft failure after two months of immunosuppressive medication nonadherence, ultimately requiring emergent hemodialysis, which was complicated by new onset seizures. This was the patient’s fourth episode of late acute rejection and emphasizes the need for education of immunosuppressant adherence and periodic monitoring of renal function in high-risk patients. Though there is no known creatinine level incompatible with life, this patient appears to have the highest known serum creatinine in a uremic patient on record.

Serum creatinine is a commonly used laboratory measurement to gauge renal function in clinical practice. Creatinine is a byproduct of the metabolism of creatine in skeletal muscle and dietary meat intake [1]. It is freely filtered across the glomerulus, and there is additional creatinine secretion in the proximal tubule of the nephron via organic cation secretory pathways [2]. Therefore, serum creatinine is a reflection of glomerular filtration rate, creatinine secretion in the renal tubule, creatine intake, and baseline skeletal muscle mass. Creatinine is also known to vary by gender and race, with average values of 1.14 mg/dL in men and 0.93 mg/dL in women in the United States [3]. The previously highest serum creatinine reported was 53 mg/dL [4]. In current clinical practice, there remains uncertainty regarding the role of serum creatinine and mortality, specifically in the context of the degree of creatinine elevation. We present a case of acute renal allograft rejection with the highest serum creatinine reported in previous literature.

We report a 23-year-old African American male with a medical history of pediatric DDRT secondary to left-sided dysplastic kidney and right-sided obstructive uropathy. He presented to the emergency department with a one-week history of decreasing urine output, increased shortness of breath, generalized weakness, and nausea. He initially received his DDKT in 2010, which has been complicated by multiple episodes of both acute T cell-mediated and acute antibody-mediated rejection. The patient admitted to a two-month history of immunosuppressive medication nonadherence with tacrolimus, mycophenolate, and prednisone.

Physical examination revealed a young male, in no distress, weighing 142 pounds. He had a blood pressure of 153/102 mmHg and a heart rate of 77 beats/min. Exam findings are as follows: pale conjunctiva, lungs clear to auscultation, regular heart rate and rhythm, active bowel sounds, no abdominal tenderness, and no focal neurological deficit. Admission labs included a serum creatinine of 64.6 mg/dL (0.67–1.17 mg/dL) with a blood urea nitrogen (BUN) of 212 mg/dL (6–20 mg/dL), which increased to a serum creatinine of 73.8 mg/dL and BUN of 244 mg/dL prior to initiation of emergent dialysis. Serum chemistry included sodium 137 mmol/L (136–145 mmol/L), potassium 6.0 mmol/L (3.5–5.1 mmol/L), chloride 98 mmol/L (98–107 mmol/L), total carbon dioxide 7 mmol/L (22–29 mmol/L), glucose 68 mg/dL (74–106 mg/dL), and phosphorus 14.7 mg/dL (2.7–4.5 mg/dL).

The patient was initiated on emergent dialysis via a temporary dialysis catheter. Dialysis was complicated by new onset of seizures, initially thought to be secondary to dialysis disequilibrium syndrome. An electroencephalogram (EEG) was performed showing right temporal spikes epileptiform discharges with intermittent slow waves lateralized to the right hemisphere. Patient was thought to have epilepsy with initial seizure exacerbation secondary to severe metabolic derangements in setting of acute renal failure and severe azotemia. He was initiated on daily levetiracetam with resolution of seizures.

Patient received continuous renal replacement therapy (CRRT) while in the intensive care unit. After stabilization of his acute medical issues, a tunneled dialysis catheter was placed in his right internal jugular vein prior to discharge. Ultimately, the patient was diagnosed with renal allograft failure secondary to medication nonadherence and was discharged home on intermittent hemodialysis with improvement in serum creatinine to 23.8 mg/dL and BUN of 76 mg/dL at time of discharge, after completion of four hemodialysis sessions.

This case demonstrated a record high serum creatinine of 73.8 mg/dL based on our review of previous literature [4–7]. Currently, there is not a known effect of creatinine levels on human physiology or survivability [5]. Even with its inherent limitations, previous studies have explored the relationship between increased serum creatinine and mortality. In a prospective population-based study of people >65 years old, 11.2% of the population had an elevated serum creatinine (>1.5 mg/dL in men and >1.3 mg/dL in women) which was associated with a higher overall mortality (76.7 vs. 29.5/1000 years) [8]. In a retrospective study of hospitalized patients, very low serum creatinine admission value of <0. 4 mg/dL was significantly associated with increased mortality, exceeding the risk related to a creatinine value of >1.5 mg/dL [9].

This patient had elevated creatinine secondary to acute renal allograft rejection. Acute allograft rejection is a functional deterioration of the allograft caused by specific pathologic changes due to recipient’s immune system recognizing nonself-antigens from the allograft [10]. Typically, such rejection leads to subsequent rise in serum creatinine indicating substantial histological damages without significant symptom manifestation [11]. The long-term function of a renal allograft is associated significantly with acute rejection episodes, especially late acute rejections [12]. Late acute rejections occur greater than 3 months after transplant, and this case represented the patient’s fourth episode of such. In a previous historical cohort study, the late acute rejection group was shown to have the highest amount of graft loss when compared to the no rejection and early acute rejection groups [12]. This patient was ultimately diagnosed with renal allograft failure and remained dialysis dependent after discharge.

Our patient showed minimal symptoms initially, likely related more to azotemia and metabolic derangements rather than the elevated serum creatinine level. Chronic kidney disease (CKD) symptoms typically do not manifest until KDIGO CKD stages IV and V [13]. Chronic kidney disease is commonly detected by routine urine testing and labs, as it initially can present asymptomatically [13]. This case demonstrates the importance of periodic lab evaluation to assess kidney function in high-risk renal patients and the need for counseling on the importance of medication adherence. There is no known creatinine incompatible with life, and this patient appears to have the highest survivable serum creatinine recorded in the medical literature.

The views expressed in this material are those of the authors and do not reflect the official policy or position of the U.S. Government, the Department of Defense or the Department of the Air Force.

The authors declare that they have no conflicts of interest.

1. Levey A. S., Perrone R. D., Madias N. E. Serum creatinine and renal function.
Annual Review of Medicine
. 1988;39(1):465–490. doi: 10.1146/annurev.me.39.020188.002341. [PubMed] [CrossRef] [Google Scholar]

2. Shemesh O., Golbetz H., Kriss J. P., Myers B. D. Limitations of creatinine as a filtration marker in glomerulopathic patients.
Kidney International
. 1985;28(5):830–838. doi: 10.1038/ki.1985.205. [PubMed] [CrossRef] [Google Scholar]

3. Jones C., McQuillan G., Kusek J., et al. Serum creatinine levels in the US population: third national health and nutrition examination survey.
American Journal of Kidney Diseases
. 1998;32(6):992–999. doi: 10.1016/s0272-6386(98)70074-5. [PubMed] [CrossRef] [Google Scholar]

4. Asif A. A., Hussain H., Chatterjee T. Extraordinary creatinine level: a case report.
Cureus
. 2020;12 doi: 10.7759/cureus.9076. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

5. Storm A. C., Htike N. L., Cohen D. A., Benz R. L. A surviving patient with record high creatinine.
Open Journal of Nephrology
. 2013;3(4):217–219. doi: 10.4236/ojneph.2013.34037. [CrossRef] [Google Scholar]

6. Master Sankar Raj V., Garcia J., Gordillo R. 17 year-old boy with renal failure and the highest reported creatinine in pediatric literature.
Case Reports in Pediatrics
. 2015;2015:4. doi: 10.1155/2015/703960.703960 [PMC free article] [PubMed] [CrossRef] [Google Scholar]

7. Abuhasna S. D. Highest serum creatinine ever reported.
Hemodialysis International
. 2012;17(1):137–138. doi: 10.1111/j.1542-4758.2012.00725.x. [PubMed] [CrossRef] [Google Scholar]

8. Fried L. F., Shlipak M. G., Crump C., et al. Renal insufficiency as a predictor of cardiovascular outcomes and mortality in elderly individuals.
Journal of the American College of Cardiology
. 2003;41(8):1364–1372. doi: 10.1016/s0735-1097(03)00163-3. [PubMed] [CrossRef] [Google Scholar]

9. Thongprayoon C., Cheungpasitporn W., Kittanamongkolchai W., Harrison A. M., Kashani K. Prognostic importance of low admission serum creatinine concentration for mortality in hospitalized patients.
The American Journal of Medicine
. 2017;130(5):545–554. doi: 10.1016/j.amjmed.2016.11.020. [PubMed] [CrossRef] [Google Scholar]

10. Naik R.
Renal Transplantation Rejection
. Treasure Island, FL, USA: StatPearls Publishing; 2020.
https://www.statpearls.com/articlelibrary/viewarticle/17170/
[Google Scholar]

11. Reisner H., Jennette J. C., Hussein Gasim A. M.
Pathology: A Modern Case Study
. 2nd . Chapel Hill, NC, USA: McGraw-Hill; 2015. Chapter 13: pathology of medical renal disease. [Google Scholar]

12. Jalalzadeh M., Mousavinasab N., Peyrovi S., Ghadiani M. H. The impact of acute rejection in kidney transplantation on long-term allograft and patient outcome.
Nephro-Urology Monthly
. 2015;7(1) doi: 10.5812/numonthly.24439.e24439 [PMC free article] [PubMed] [CrossRef] [Google Scholar]

13. Vaidya S.
Chronic Renal Failure
. Treasure Island, FL, USA: StatPearls Publishing; 2020.
https://www.statpearls.com/articlelibrary/viewarticle/28357/
[Google Scholar]

Articles from Case Reports in Nephrology are provided here courtesy of Hindawi Limited

Creatinine blood test Information | Mount Sinai

Serum creatinine; Kidney function – creatinine; Renal function – creatinine

The creatinine blood test measures the level of creatinine in the blood. This test is done to see how well your kidneys are working.

Creatinine can also be measured with a urine test.

A measurement of the serum creatinine level is often used to evaluate kidney function. Urine creatinine levels can be used as a screening test to evaluate kidney function, or can be part of the creatinine clearance test.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

The health care provider may tell you to temporarily stop taking certain medicines that can affect the test. These medicines include:

• Cimetidine, famotidine, and ranitidine
• Certain antibiotics, such as cefoxitin and trimethoprim

Tell your provider about all the medicines you take.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or slight bruising. This soon goes away.

Why the Test is Performed

Creatinine is a chemical waste product of creatine. Creatine is a chemical made by the body and is used to supply energy mainly to muscles.

This test is done to see how well your kidneys work. Creatinine is removed from the body entirely by the kidneys. If kidney function is not normal, the creatinine level in your blood will increase. This is because less creatinine is excreted through your urine.

Normal Results

A normal result is 0. 7 to 1.3 mg/dL (61.9 to 114.9 µmol/L) for men and 0.6 to 1.1 mg/dL (53 to 97.2 µmol/L) for women.

Women often have a lower creatinine level than men. This is because women often have less muscle mass than men. Creatinine level varies based on a person’s size and muscle mass.

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

A higher than normal level may be due to:

• Blocked urinary tract
• Kidney problems, such as kidney damage or failure, infection, or reduced blood flow
• Loss of body fluid (dehydration)
• Muscle problems, such as breakdown of muscle fibers (rhabdomyolysis)
• Problems during pregnancy, such as seizures caused by eclampsia or high blood pressure caused by preeclampsia

A lower than normal level may be due to:

• Conditions involving the muscles and nerves that lead to decreased muscle mass
• Malnutrition

There are many other conditions for which the test may be ordered, such as high blood pressure, diabetes, or medicine overdose. Your provider will tell you more, if needed.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Multiple punctures to locate veins
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Landry DW, Bazari H. Approach to the patient with renal disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 106.

Oh MS, Briefel G, Pincus MR. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 15.

Last reviewed on: 7/21/2021

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

what does this mean, norms and causes of increased rates

What is creatinine?

Creatinine is a chemical compound in the human body, which is formed during the breakdown of protein molecules. The substance is part of the residual nitrogen. The beginning of the chain is creatine, a component that moves throughout the body, starting from the renal parenchyma.

The methylation process takes place in the liver. After that, creatine enters the muscles, where it is converted to creatine phosphate. The latter enters the myofibrils and decomposes into phosphate and creatinine. Muscles receive energy for contraction. The rest goes into the blood. In the liver, creatinine is not converted and is easily excreted in the urine. Energy turnover is constantly happening. In a healthy body, the amount of a substance is always stable.

Creatinine in Moscow

from 1 cal. days

from 229 ₽

Daily urine creatinine in Moscow

from 1 cal. days

from 249 ₽

Coronavirus, RNA (SARS-CoV-2, PCR) smear, quality in Moscow

from 1 cal. days

from 999 ₽

Depending on the health of the kidneys and the state of the muscles, the level of creatinine changes. A decrease in this substance in the blood is required with increased breakdown of muscle tissue. This happens in the case of kidney failure, when it becomes difficult for the body to remove toxic substances.

A person can detect a deviation of creatinine from the norm independently according to the specific signs of the body. For example, kidney pathology leads to a change in the color of urine. It acquires a cloudy color, a brown tint or a shade of coffee grounds. The patient begins to go to the toilet less often, the volume of urine decreases. A typical symptom is the accumulation of fluid in the abdominal cavity and swelling of the face and extremities.

When urinating, it hurts a person, he feels pain. Pain when the situation worsens may appear in the hypochondrium or in the lumbar region. People get tired quickly, when they wake up they immediately feel weak, appetite decreases, attention is disturbed, it is difficult to concentrate on one thing. Insomnia appears, blood pressure either goes down or goes up. Infectious lesions of the kidneys are accompanied by fever.

Creatinine norm

The norm of creatinine depends entirely on the level of accumulation of muscle mass in the body. The indicator is usually denoted in microcol / l. Normative values ​​are not the same throughout life. In men with good health, the rate is always higher than that of women. In general, for children and adults, the following standard indicators can be compiled, measured in µmol / l:

• in women under 60 years old – 53-97, over 60 years old – 53-106;
• in men under 60 years old – 80-115, over 60 years old – 71-115;
• in children in the newborn state – 27-88, up to 1 year – 18-35, from one year to 10 years – 27-62 and from 10 to 18 years – 44-88.

The required amount of a substance is calculated based on the total mass of a person, the level of his physical endurance, activity in everyday life. What causes the fact that the norm of creatinine in a blood test for men, women and children is significantly different.

Gender, weight, age of the patient are mandatory criteria for evaluation. This makes it possible to classify a biochemical blood test for creatinine as an exclusively primary diagnostic method. It is noted that the criterion is characterized by a greater degree of sensitivity to kidney pathologies than urea.

It should be understood that creatinine can decrease not only against the background of pathological problems. Strong physical overstrain or overwork will certainly affect the analysis. This includes the delivery of creatinine after several days of feasting, where predominantly meat food prevailed and there was a lot of alcohol.

If there has been a state of dehydration, leading to thickening of the blood, then the creatinine level temporarily increases. Many drugs, if taken uncontrollably, can have a toxic effect on the urinary organs.

Indications for creatinine testing

Creatinine analysis helps to evaluate the filtration function of the kidneys. It is also prescribed for severe injuries and diagnosed diseases of varying degrees of course. It also allows you to evaluate the efficiency of renal filtration of small molecules and to diagnose the glomerular filtration rate. The main indications are:

• known renal insufficiency or suspected disease;
• different degrees of kidney disease, including pyelonephritis, polycystic disease, urolithiasis, glomerulonephritis;
• burns and injuries;
• muscle atrophy;
• endocrine diseases;
• problems with the cardiovascular system;
• acute inflammation;
• sepsis;
• recovery period after surgical interventions.

Preparing for a creatinine test

Biochemical analysis is carried out with a certain preparation. Firstly, it is done on an empty stomach and always in the morning. The day before the analysis, the last time they eat is no later than 20 pm. And in one day it is important to comply with the following conditions:

• do not stress and get enough sleep;
• do not overwork physically and do not do complex exercises, such as push-ups with dumbbells;
• avoid overheating, including sauna visits;
• do not drink alcoholic beverages;
• do not eat fatty foods and try to eat less meat;
• avoid spicy and salty foods;
• do not smoke 2 hours before the analysis.

Incorrect sampling of biomaterial can lead to unreliable results. This leads to the destruction of red blood cells. Their contents are released. The result is a distorted biochemical composition of the blood. In this case, a retest is simply necessary.

False positive results can occur in the presence of a large amount of muscle mass. If a weightlifter passes the diagnosis, then this fact should be taken into account. The result is affected by diabetes mellitus in the patient’s history, against which the concentration of simple sugars, acetone and urea increases. With muscle damage, as well as against the background of taking medications such as barbiturates or aminoglycoside antibiotics, creatinine readings are distorted.

Elevated creatinine

A person is in energy exchange throughout his life. A slight deviation of creatinine from the norm is not considered a problem. But if this excess is significant and is observed regularly, then there are definitely problems.

An increase in creatinine is indicated by weakness, drowsiness and loss of strength. You may feel dizzy and have a nausea reflex. Breathing quickens, a person does not get fresh air. These are indirect signs of kidney failure with a high level of creatinine in the blood. May indicate inflammation and destruction in the muscular system, infectious diseases leading to kidney damage.

What does elevated creatinine indicate?

Elevated creatinine in human blood can be associated with two reasons: physiological or pathological. The first option is associated with a large amount of muscle mass as a result of intense physical exercise. Such cases occur among people who do a lot and often do wrestling, powerlifting and bodybuilding.

Those who cannot imagine life without meat are also prone to increased creatinine levels. In many cases, the uncontrolled use of drugs leads to the need to reduce the creatinine level. It is especially dangerous to use tetracycline antibiotics, cephalosporins, non-steroidal anti-inflammatory drugs without the advice of a doctor.

Elevated creatinine can also speak of pathological disorders in the body. For example, an increase in the rate is often observed in case of kidney diseases in the acute and chronic stages, as well as in violation of the patency of the urinary tract. The kidneys can suffer due to impaired blood supply, which sooner or later leads to serious pathologies of the cardiovascular system.

Radiation sickness or oncological diseases can lead to constant jumps in creatinine. Septic shock, burns of varying severity, as well as diagnosed endocrine pathologies can cause changes in the indicator.

Causes of elevated creatinine

The main reason for the increase in the indicator is its increased production or poor excretion process from the body. This phenomenon is typical when diagnosing the following pathologies:

• liver problems, including inflammation, toxic poisoning and cirrhosis;
• necrosis of internal organs due to damage to cells and tissues;
• renal insufficiency;
• increased level of the thyroid gland;
• muscle and bone lesions;
• second and third degree burns;
• vascular lesions in the kidneys;
• complication after diabetes mellitus;
• weakness of the muscular system;
• diseases of the pulmonary system;
• fever;
• drug poisoning, manifested by toxic effects on the kidneys.

Fasting, pregnancy and long-term treatment with corticosteroids can cause temporary phenomena of an increase in the indicator.

How to lower blood creatinine?

It is almost impossible to lower the blood count on your own. This is due to the fact that one cannot do without passing certain tests and consulting with a specialist. It is important to adhere to competent treatment and limit nutrition in accordance with the recommendations of the doctor. During the diagnosis, a serious pathology may be revealed, without the treatment of which it is impossible to adjust the level of creatinine in the blood.

If a patient’s creatinine is elevated as a result of improper and unbalanced nutrition, then in order to restore the indicator, it is necessary to abandon the use of a number of products. These include primarily fatty meats and fish, smoked and spicy foods, dairy products, cheeses, salt, sugar, and strong drinks such as coffee and black tea.

The food should contain a minimum of protein and salt. Try to eat foods that contain antioxidants. These include cabbage, beans, walnuts, pistachios, strawberries, oranges, tangerines, eggplants. Drink at least a liter of pure water per day. Specialists can prescribe a course of taking special drugs that will help to cope with the problem quickly and efficiently.

It should be temporarily canceled toxic drugs and anabolic hormones. In case of kidney failure or in case of serious injury, special treatment is prescribed. It is important to restore the patency of the renal tubules and normalize blood flow. The damaged surface will close faster and the shock will pass. Thyrotoxicosis requires drugs that suppress excessive thyroid function.

If, after the measures taken, the indicators do not give a positive trend and a return to normal is not expected, then it is necessary to adjust the approach to treatment. Perhaps the connection of fasting days is required to reduce the load on the organs and urinary systems.

Creatinine decreased

When an amino acid is used by the body for energy, part of it is consumed according to needs. The remaining creatinine remains as waste. Decreased creatinine is often seen in vegetarians and pregnant women. In the first case, the problem is the lack of animal products, leading to protein deficiency in the body, and consequently, to muscle weakness with subsequent atrophy. During the bearing of a child, a physiological mechanism takes place, during which the total volume of blood increases. In many older people, this figure goes down, but should not cause concern.

Causes of low creatinine

It can be concluded that a reduced level of creatinine is observed in the following cases:

• For low muscle mass. The share of muscles may decrease against the background of a sharp weight loss. For example, during illness or due to age.
• In diseases of the liver. If the liver is not healthy, then it cannot fully produce creatinine. Chronic disease of this organ can provoke a 50% shortage of creatinine. It is easy to detect this with a simple blood test.
• Long diets. Creatinine is mostly produced naturally, but some part comes with the food you eat. If a person abruptly stops eating as before, for example, switches to a vegetarian diet, then the level of creatinine decreases rapidly.
• During childbearing. The baby also needs a lot of strength and energy for development. Mommy’s body divides all the reserves into two. Therefore, in her body, you can often fix the level of decrease in creatinine. After childbirth, this indicator quickly returns to normal.

Severe weakness and the inability to perform the simplest physical exercises can indicate a low level of creatinine. With problems with the liver, the patient notices discomfort in the upper abdomen, he is sick and shivering. With a diet, weakness is accompanied by dizziness, weight quickly falls.

Serum creatinine (with GFR)

Creatinine is a non-enzymatic breakdown product of creatine and creatine phosphate, formed in muscle. It is excreted from the body by the kidneys.

Synonyms Russian

1-methylglycocyamidine, a product of the conversion of creatine phosphate, creatinine in the blood.

Synonyms English

Research method

Kinetic method (Jaffe method).

Units

µmol/l (micromoles per litre).

What biomaterial can be used for research?

Venous blood.

How to properly prepare for the examination?

• Do not eat for 12 hours before the test.
• 30 minutes before the study, exclude physical and emotional overstrain.
• Do not smoke for 30 minutes before the test.

Study Overview

Creatinine is a waste product produced in muscles when a substance called creatine is broken down. Creatine is part of the cycle that provides the body with energy for muscle contraction. After 7 seconds of intense physical activity, creatine phosphate is converted to creatine, then turns into creatinine, which is filtered in the kidneys and excreted in the urine. Creatine and creatinine are stably produced by our body in a constant amount. Almost all creatinine is excreted by the kidneys, so its concentration in the blood is a good indicator of their function. The amount of creatinine produced depends on the total body weight and, in particular, muscle mass. Therefore, for example, creatinine levels in men will be significantly higher than in women and children.

A minor part (15%) is secreted by the tubules, but it is mainly produced by filtration in the glomerulus. The level of creatinine in the blood does not go beyond the norm until the glomerular filtration rate drops to critical values, especially in patients with low muscle mass. Then the creatinine level rises.

Precisely because of the large number of factors (muscle mass, sex, age) that affect the concentration of creatinine in the blood, this study is not the best screening test for detecting kidney failure. At the same time, creatinine is a more sensitive indicator of kidney disease than urea.

What is research used for?

• To assess kidney function.
• To assess the function of the main organs and systems (in combination with other studies).
• To assess renal dysfunction and the effectiveness of its treatment, if creatinine or urea is abnormal and the patient has some underlying chronic disease, such as diabetes, the course of which affects the condition of the kidneys.
• If blood and urine creatinine levels are known, creatinine clearance (Rehberg’s test) can be calculated – this test shows how efficiently the kidneys filter small molecules, such as creatinine, from the blood.
• To calculate glomerular filtration rate to confirm kidney damage.

When is the test scheduled?

• At regular intervals for known kidney disease or disease that can cause deterioration of kidney function (in conjunction with urea and microalbuminuria test).
• In the diagnosis of skeletal muscle diseases.
• Before and after hemodialysis.
• For symptoms of kidney dysfunction:
  • weakness, fatigue, decreased attention, poor appetite, sleep problems,
  • swelling of the face, wrists, ankles, ascites,
  • Foamy, red or coffee-colored urine,
  • decreased diuresis,
  • problems with the act of urination: burning, discontinuity, change in frequency (dominance of nocturnal diuresis),
  • pain in the lumbar region (especially on the sides of the spine), under the ribs,
  • high pressure.
• For any pathological conditions accompanied by dehydration.
• In preparation for a CT scan.
• Before prescribing drugs that can cause damage to the kidney tissue.

What do the results mean?

Reference values ​​(creatinine norm):

Creatinine

GFR (glomerular filtration rate): 60 or more.

Causes of increased creatinine levels

• Acute and chronic renal failure (amyloidosis, kidney damage in diabetes mellitus, etc.).
• Failure of the cardiovascular system (myocardial infarction, cardiogenic shock, myocardial dystrophy, etc.).
• Massive destruction of muscle tissue (crash syndrome) and release of creatinine from cells.
• Burns (massive necrosis of cells with the release of their contents into the intercellular substance).
• Acromegaly.
• Gigantism.
• Hyperthyroidism.
• Dehydration (blood clotting and relative hypercreatininemia).
• Excessive exercise.
• Excess consumption of meat products.
• Radiation sickness.
• Obstruction of the urinary tract.
• Taking nephrotoxic drugs (mercury compounds, sulfonamides, thiazides, antibiotics from the group of aminoglycosides, cephalosporins and tetracyclines, barbiturates, salicylates, androgens, cimetidine, trimethoprim-sulfamethoxazole).
• Damage to the vessels of the glomerular apparatus of the kidneys (glomerulonephritis), which may be the result of an infectious or autoimmune disease.
• Bacterial infection of the kidneys (pyelonephritis).
• Necrosis of tubular epithelium (acute tubular necrosis) caused, for example, by drugs or toxins.
• Diseases of the prostate, nephrolithiasis or other factors causing obstruction of the urinary system.
• Decreased blood flow to the kidneys due to shock, dehydration, acute heart failure, atherosclerosis, or complications of diabetes.

Causes of low creatinine levels

• Fasting.
• Hyperhydration (blood dilution – relative hypocreatininemia).
• Muscle atrophy.

What can influence the result?

• Confounding factors
  • Pregnancy (especially I and II trimesters).
• Performance enhancing factors
  • Excessive muscle mass, such as in some athletes (may increase creatinine levels despite normal kidney function).