Kidney Function Tests

A brief on Kidney Function Tests

This panel is used to assess the functioning of your kidney. Kidneys have multiple functions including filtering blood in your body to remove waste products.

  • Urea: Urea is the nitrogenous waste product generated from protein breakdown. It is eliminated from the body almost exclusively by the kidneys through urine. Urea levels are seen to vary with levels of hydration and diet of an individual.
  • BUN (Blood Urea Nitrogen):): Its value depends on levels of blood urea and is calculated based on it.
  • Creatinine:Creatinine is a waste product and is cleared from the blood entirely by the kidney. Decreased clearance by the kidney results in increased blood creatinine.

    The amount of creatinine produced per day depends on muscle bulk. Thus there is a difference in creatinine ranges between males and females, with lower creatinine values in children and those with increased muscle bulk. Diet and exercise also influences creatinine value. Creatinine can change as much as 30% after ingestion of red meat and exercise. Creatinine values are used as an indicator of the functioning of your kidney.

  • Uric Acid: Uric acid is another waste product in your body. Consistently high levels of uric acid can lead to problems such as gout.
  • Some causes for a high uric acid level:
    • Alcohol, high fat diet, fast foods along with poor hydration.
    • Intake of red meats and also prolonged duration of fasting.
    • Certain medicines - ask your doctor.
  • Sodium: Sodium is an electrolyte that is vital to nerve and muscle and brain function and helps regulate the amount of fluid in the body. We get sodium in our diet from table salt (NaCl) and some degree from most of the foods that we eat. Its levels help evaluate conditions such as dehydration, edema, heart, lung or kidney disease.
  • Potassium: Potassium is an electrolyte that plays an important role to control your body’s fluid levels, acid-base balance, and nerve and muscle activity. Potassium is an essential nutrient that you consume in your daily diet. Potassium rich foods include bananas, citrus fruits and certain green vegetables. In certain conditions, abnormal levels may be used to assess the functioning of vital organs such as heart and kidney.
  • Chloride: Chloride is an electrolyte that is a type of a mineral which helps in regulating the amount of fluid in your body. It also helps in maintaining the body's acid-base balance. An appropriate acid-base balance is fundamental to your body’s major systems like cardiovascular, nervous, respiratory and metabolic systems.
  • Amylase: Amylase is an enzyme secreted by the pancreas and salivary gland that helps in breakdown of carbohydrates. Significantly elevated levels of amylase may indicate a disorder of the pancreas.
  • C.P.K. (Creatine Phosphokinase): CPK is an enzyme found primarily in skeletal and cardiac muscle. It is commonly seen to be elevated in individuals performing strenuous exercise or on cholesterol lowering drugs. It’s also elevated in diseases like Muscular dystrophy, Myopathies, Polymyositis, Muscle trauma and Myocardial infarction, etc. A cardiac enzymes study is advised in patients with clinical signs & elevated levels to rule out myocardial infarction. Clinical correlation is mandatory in such cases.
Understanding Kidney Function Tests (KFTs): Evaluating Renal Health
  • Evaluates the health and efficiency of your kidneys.
  • Involves several parameters, including creatinine, BUN (blood urea nitrogen), electolytes and GFR (glomerular filtration rate).
  • Creatinine: A waste product; elevated levels may indicate kidney dysfunction.
  • Causes of derangement: kidney disease, dehydration, certain medications.
  • BUN (Blood Urea Nitrogen): Measures the amount of urea nitrogen in your blood; increased levels may indicate kidney or liver issues.
  • Causes of derangement: kidney problems, heart failure, dehydration, high protein intake.
  • GFR (Glomerular Filtration Rate): Estimates the rate at which your kidneys filter blood; a lower GFR may indicate decreased kidney function.
  • Causes of derangement: kidney disease, aging, certain medications.
Reference Ranges:
  • UREA,Serum [Kinetic Method] - 16.6 - 48.5 mg/dL
  • BUN (BLOOD UREA NITROGEN),Serum [KineticMethod]- 7.7 - 22.7 mg/dL
  • CREATININE,Serum [Kinetic Jaffes method ] - 0.9-1.3 mg/dL
  • URIC ACID,Serum [Enzymatic Assay] - 3.5 - 7.2 mg/dL
  • PHOSPHORUS,Serum [Molybdate UV ] - 2.5-4.5 mg/dL
  • SODIUM,Serum [Indirect ISE method] - 136 - 145 mmol/L
  • POTASSIUM,Serum [Indirect ISE method]- 3.5 - 5.1 mmol/L
  • CHLORIDE,Serum [Indirect ISE method] - 98 - 107 mmol/L
  • TOTAL CALCIUM,Serum [BAPTA Method] - 8.6-10 mg/dL
  • IONIZED CALCIUM, Serum [BAPTA Method] - 1.1-1.25 mmol/L
  • TOTAL PROTEINS,Serum [Biuret method ] - 6.4-8.3 g/dL
  • ALBUMIN,Serum [Colorimetric BCG]- 3.5-5.2 g/dL
  • GLOBULIN,Serum [Calculated] - g/dL
  • ALBUMIN/GLOBULIN RATIO [Calculated] 1.1 - 2.2
  • EGFR [Calculated] - 60-120 ml/min/1.73m2
Interpretation of Kidney Function Test Results:

    High Creatinine and BUN: Elevated levels may indicate reduced kidney function or kidney disease.

    Low eGFR: Reduced eGFR might suggest decreased kidney function, especially when coupled with high creatinine levels.

    Electrolyte Imbalances: Abnormal levels might signal kidney-related electrolyte imbalances, potentially affecting various bodily functions.

FAQ - Common Questions:

    Question:What is a Kidney Function Test, and why is it important?
    Answer:It assesses how well your kidneys are filtering waste and maintaining your body's balance.

    Question:What does high creatinine indicate in the test?
    Answer:Elevated creatinine levels can suggest kidney dysfunction or other health issues.

    Question:Why might my BUN levels be high in a Kidney Function Test?
    Answer:High BUN levels can be due to kidney problems, dehydration, or a high-protein diet.

    Question:What does GFR tell us, and what does a low GFR indicate?
    Answer:GFR estimates kidney filtration rate; a low GFR may suggest reduced kidney function.

    Question:What can I do to maintain good kidney health?
    Answer:Stay hydrated, manage chronic conditions like diabetes, and avoid excessive salt intake.

    Question:Can medications affect Kidney Function Test results?
    Answer:Yes, certain medications can impact the test, so inform your healthcare provider about all medications you take.

    Question:Is it normal for Kidney Function Test results to vary over time?
    Answer:Yes, slight variations can occur, but significant changes may warrant further investigation.

    Question:What should I do if my Kidney Function Test results are abnormal?
    Answer:Consult your healthcare provider for a proper evaluation and guidance.

    Question:How often should I have a Kidney Function Test?
    Answer:Your doctor will determine the frequency based on your health and risk factors.

    Question:Can a healthy diet help maintain kidney function?
    Answer:Yes, a balanced diet with limited salt and protein can support kidney health; consult a dietitian for guidance.

Questions to Ask Your Doctor about KFT:

    When discussing your Kidney Function Test results with your doctor, consider asking:

    • Interpretation of Results: What do my Kidney Function Test results indicate about my kidney health? Are there any concerns or abnormalities?
    • Creatinine and BUN Levels Interpretation: How do my creatinine and BUN levels compare to the recommended ranges?
    • eGFR Interpretation: What does my eGFR value suggest about my kidney function? Is a low eGFR a cause for concern?
    • Potential Causes of Abnormal Results: Besides kidney-related issues, what other factors might contribute to abnormal Kidney Function Test results?
    • Chronic Kidney Disease Risk: What is my risk of chronic kidney disease based on these test results and other health factors?
    • Management of Kidney Disease: If kidney disease is detected, what treatment options or lifestyle changes are recommended to manage it?
    • Follow-up Testing or Monitoring: How frequently should I have follow-up Kidney Function Tests or other assessments to monitor kidney health?
    • Effects of Medications on Kidneys: Can certain medications affect kidney function, and should their dosage be adjusted based on these results?
    • Dietary Adjustments for Kidney Health: Are there specific dietary recommendations to support kidney health and prevent further damage?