Carbon Dioxide
mmol/L
CO2 levels reflect acid-base balance and respiratory function, essential for cellular metabolism and pH homeostasis.
Optimal Range
22-28 mEq/L
optimal 24-26 mEq/L for acid-base balance
EssentialAdvancedMax
Your kidneys filter about 200 litres of blood daily, maintaining fluid balance, electrolyte levels, and waste removal. This panel measures markers that reveal how effectively your kidneys are performing these essential functions.
CO2 levels reflect acid-base balance and respiratory function, essential for cellular metabolism and pH homeostasis.
Optimal Range
22-28 mEq/L
optimal 24-26 mEq/L for acid-base balance
Potassium is essential for heart function, muscle contraction, and blood pressure regulation, with deficiency being extremely common.
Optimal Range
3.5-5.0 mEq/L
optimal 4.0-4.5 mEq/L for cardiovascular health
Sodium regulates fluid balance, nerve function, and blood pressure, serving as a key indicator of hydration and electrolyte status.
Optimal Range
136-145 mEq/L
optimal 138-142 mEq/L for cellular function
Chloride maintains fluid balance and enables stomach acid production, essential for digestion and acid-base homeostasis.
Optimal Range
98-107 mEq/L
optimal 100-105 mEq/L for acid-base balance
BUN/creatinine ratio differentiates causes of kidney dysfunction and assesses hydration status and protein metabolism.
Optimal Range
10-20:1
optimal 12-16:1 for kidney and hydration assessment
eGFR measures kidney filtration capacity, essential for toxin elimination, blood pressure control, and healthy aging.
Optimal Range
>90 mL/min/1.73m²
optimal >100 mL/min/1.73m² for longevity
Creatinine measures kidney filtration capacity and muscle metabolism, serving as the primary indicator of kidney health and detoxification.
Optimal Range
Men: 0.8-1.2 mg/dL
Women: 0.6-1.0 mg/dL
optimal lower half of range
BUN reflects kidney filtration capacity and protein metabolism. Optimal levels indicate healthy kidney function and appropriate protein processing by the liver.
Optimal Range
7-20 mg/dL
optimal 8-18 mg/dL
Uric acid reflects purine metabolism and kidney function. Optimal levels prevent gout, kidney stones, and reduce cardiovascular disease risk.
Optimal Range
Male: 3.7-8.6 mg/dL
Female: 2.6-6.0 mg/dL
optimal Male: 4.0-6.5 mg/dL
Female: 3.0-5.5 mg/dL
Kidney Health
Kidney Health
Your kidneys perform a feat of extraordinary precision: filtering approximately 200 litres of blood every day while selectively retaining what your body needs and excreting what it doesn't. They regulate blood pressure via the renin-angiotensin-aldosterone system, maintain the body's pH balance, control fluid volume, activate vitamin D, and signal the bone marrow to produce red blood cells through erythropoietin secretion. The kidneys are simultaneously a filtration organ, an endocrine gland, and a metabolic regulator.
Chronic kidney disease (CKD) affects approximately 850 million people worldwide — more than diabetes and cancer combined. The disease is characterised by its silence: most people have no symptoms until kidney function falls below 20–25% of normal, by which point fibrosis and structural damage are often irreversible. Blood-based markers — particularly eGFR, creatinine, cystatin C, and BUN — combined with urine albumin-to-creatinine ratio, provide a sensitive early warning system that enables intervention years before kidney function becomes clinically critical.
Kidney health does not exist in isolation — it is deeply intertwined with every major system.
The kidney-heart connection is bidirectional and powerful. Kidneys regulate blood pressure by controlling fluid volume and secreting renin, which drives angiotensin II production and aldosterone release. Hypertension damages glomerular capillaries over decades, progressing to CKD. Conversely, kidney disease elevates blood pressure through fluid retention and renin excess, creating a self-amplifying cycle. CKD is a more powerful independent risk factor for cardiovascular mortality than most traditional risk factors — at eGFR below 60, cardiovascular death risk doubles.
The kidneys activate vitamin D by converting 25(OH)D to its active form 1,25-dihydroxyvitamin D (calcitriol), which drives intestinal calcium absorption. As CKD progresses, calcitriol production declines, causing hypocalcaemia. The parathyroid glands respond by secreting more PTH (secondary hyperparathyroidism), which leaches calcium from bone to normalise blood levels — a process called renal osteodystrophy. Elevated phosphate (as kidneys fail to excrete it) accelerates vascular calcification, further increasing cardiovascular risk in CKD.
Peritubular cells in the kidney cortex are the primary site of erythropoietin synthesis. EPO secretion rises in response to hypoxia (low oxygen delivery) and drives red cell production in bone marrow. In CKD, both reduced EPO secretion and the toxic effects of uraemic compounds on bone marrow cause normochromic normocytic anaemia that worsens with disease progression. The resulting fatigue and reduced exercise tolerance further accelerate cardiovascular deconditioning in CKD patients.
The kidneys maintain serum potassium within the narrow 3.5–5.0 mEq/L range that cardiac muscle requires for normal rhythm. In CKD, potassium excretion declines — hyperkalaemia (elevated potassium) can trigger fatal arrhythmias. The kidneys also excrete acid daily to maintain blood pH at 7.35–7.45; declining filtration capacity causes metabolic acidosis. Even mild metabolic acidosis (bicarbonate below 22 mEq/L) accelerates muscle wasting, impairs insulin signalling, and worsens bone demineralisation. Correcting acidosis with bicarbonate supplementation slows CKD progression in trials.
Clinical Note
eGFR estimation using the CKD-EPI equation has limitations in people with very high or very low muscle mass, as creatinine reflects both filtration and muscle turnover. Cystatin C is a creatinine-independent eGFR estimator that is more accurate across body compositions. When eGFR is borderline or risk factors are present, a urine albumin-to-creatinine ratio (UACR) should always be measured alongside blood markers for complete kidney health assessment.
Estimated glomerular filtration rate (eGFR) is a calculated score that estimates how many millilitres of blood your kidneys filter per minute per 1.73m² of body surface area. It is derived from serum creatinine, age, sex, and sometimes race. A normal eGFR is above 90 mL/min/1.73m². Values between 60–89 suggest mild reduction in kidney function; 30–59 indicates moderate CKD; below 30 signals severe impairment. eGFR is the primary staging criterion for chronic kidney disease (CKD) and the most informative single kidney function marker.
Creatinine is a waste product generated by the normal breakdown of creatine phosphate in muscle. Because creatinine is produced at a relatively constant rate proportional to muscle mass and is filtered and excreted almost entirely by the kidneys, its blood concentration is a reliable indicator of kidney filtration capacity. When kidneys are damaged or filtering less effectively, creatinine accumulates in the blood. Reference ranges vary by sex — men have higher muscle mass and therefore naturally higher creatinine. Optimal serum creatinine is typically 0.6–1.1 mg/dL for women and 0.7–1.3 mg/dL for men.
Blood urea nitrogen (BUN) measures urea, a waste product from protein metabolism. The BUN-to-creatinine ratio helps distinguish between different causes of elevated values. A high BUN with normal creatinine (high ratio, above 20:1) suggests dehydration or reduced blood flow to the kidneys (pre-renal azotaemia). A high ratio can also indicate high protein intake or gastrointestinal bleeding. A low ratio below 10:1 may indicate liver disease or malnutrition. Both BUN and creatinine high together (normal ratio) suggests intrinsic kidney disease.
CKD is often called a silent disease because most people have no symptoms until kidney function falls below 20–25% of normal. When symptoms do appear they include increased urination frequency (especially at night), foamy or dark urine, leg and ankle swelling from fluid retention, persistent fatigue, itching, nausea, and elevated blood pressure. Blood tests detect CKD far earlier than symptoms — eGFR decline of 5 or more mL/min/1.73m² per year is a key diagnostic indicator even when absolute values appear within range.
The kidneys are the primary regulators of electrolyte balance. Sodium controls fluid volume and blood pressure — elevated sodium suggests dehydration or sodium retention. Potassium is tightly regulated by the kidneys; elevated potassium (hyperkalaemia) in people with CKD increases cardiac arrhythmia risk. Chloride tracks with sodium and helps assess acid-base balance. Bicarbonate measures acid-base status — low bicarbonate in CKD indicates metabolic acidosis, which accelerates disease progression. Electrolyte imbalances are often among the first biochemical findings in kidney disease.
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