Kidney Function & Electrolytes explained

The kidneys filter waste from blood and hold the body's salts steady. This panel measures two waste products they clear — creatinine and urea — and the salts and minerals they regulate. Creatinine is used to estimate the filtration rate, and the KDIGO guideline sets out both how that estimate is made and where it is unreliable — muscle mass affects creatinine, so the same number does not mean the same thing in everyone. Creatinine is the filtering measure: It is converted into an estimated filtration rate, the figure used to describe kidney function as a percentage and to stage kidney disease.

Fasting: Not needed, but usually taken with a fasting panel. Best time: Morning, with the rest of the panel. Avoid beforehand: A large meat meal for 24 hours; Creatine supplements for 24 hours. Be normally hydrated. Arriving dehydrated raises urea and creatinine and makes kidney function look worse than it is.

Commonly: dehydration, the commonest cause of a mildly raised result; diabetes and high blood pressure, the leading causes of kidney damage; anti-inflammatory painkillers taken regularly; muscle mass and heavy exercise, which raise creatinine independently; a high-protein diet or creatine supplements. A single result is not a diagnosis. Values are read against the laboratory's own reference range and alongside your history, your symptoms and the rest of the panel — which is why every package includes a doctor to go through them with you.

At Smart Care Polyclinic, 29 Doha Centre, Al Maktoum Rd, Deira, Dubai. It is included in the Smart Essential Health, the Smart Total Health, the Smart Total Health 360°, the Smart Extra Health, or it can be ordered on its own. Walk in during opening hours or call +971 (0)4 379 3562.