Kidney Function

What is Kidney Function Blood Test?

The Kidney Function Blood Test is a comprehensive test that checks how well your kidneys are working. The kidneys are vital organs responsible for filtering waste products from the blood, regulating fluid balance, blood pressure, and electrolytes. This test measures seven important markers that together provide a complete picture of kidney function and electrolyte balance. It is important for fatigue, high blood pressure, swollen ankles, low urine output, or when taking medications that can strain the kidneys.

What is tested?

• Creatinine – Waste product from muscle tissue for kidney function assessment
• eGFR – Estimated glomerular filtration rate (kidney function percentage)
• Urea (BUN) – Waste product produced by the liver and excreted by the kidneys
• Sodium – Electrolyte for fluid balance and nerve function
• Potassium – Electrolyte for heart function and muscle function
• Chloride – Electrolyte for acidity and fluid balance
• Albumin – Protein for osmotic pressure; abnormalities indicate kidney or liver problems

Why should you have a Kidney Function Blood Test?

This test is crucial for early detection of kidney problems. Kidney disease often progresses silently without symptoms until severe damage occurs. The test is recommended for risk factors such as diabetes, high blood pressure, heart problems, a family history of kidney disease, or when using kidney-straining medications (painkillers, blood pressure medication, antibiotics). Kidney function should also be checked with symptoms such as fatigue, swollen ankles, low or high urine output, foamy urine, or high blood pressure. Early detection allows for treatment to prevent further deterioration.

What does it indicate?

The results show how efficiently your kidneys filter waste products and whether electrolytes are in balance:

• Filter function – Creatinine and urea rise when kidneys filter less effectively
• Kidney function percentage – eGFR indicates the percentage of normal kidney function (normal is above 90%)
• Electrolyte balance – Sodium, potassium, and chloride for heart function, nerve function, and fluid balance
• Protein loss – Albumin provides insight into protein loss through the kidneys

Disruptions can indicate kidney disease, dehydration, heart failure, or side effects of medication. This test helps detect kidney disease at an early stage when treatment is most effective.

What does a high level mean?

• Elevated creatinine and urea – Indicate reduced kidney function due to kidney disease, dehydration, medication use, or urinary tract obstruction, always requiring further investigation
• High sodium – Can indicate dehydration or hormonal problems
• High potassium – Dangerous and can lead to life-threatening cardiac arrhythmias, especially above 6.0 mmol/L, occurs with kidney disease or medications
• High chloride – Can indicate dehydration or kidney disease

Very high potassium requires immediate medical attention. These abnormalities must always be evaluated by a doctor.

What does a low level mean?

• Low eGFR (below 60 mL/min) – Indicates chronic kidney disease and requires nephrological guidance
• Low sodium – Can occur due to excessive drinking, heart failure, liver cirrhosis, or adrenal problems, causing confusion and nausea
• Low potassium – Occurs with vomiting, diarrhea, or diuretics, can lead to muscle weakness, cardiac arrhythmias, and extreme fatigue
• Low albumin – Indicates protein loss through the urine (proteinuria), which is a sign of kidney damage
• Low chloride – Can indicate vomiting, heart failure, or adrenal problems

These abnormalities require correction and monitoring to prevent serious complications.