Creatinine is a residual product released in the human body in the process of biochemical reaction during the work of muscles.  This indicator depends on the development of muscles, so newborns have creatinine levels three times lower than adults. 

Creatinine with calculation of the glomerular filtration rate (CFR) is a laboratory test that allows to assess the function of the kidneys - the ability to remove excess fluid and metabolic products from the body (filtration and purification).

For adult patients, the CKD-EPI formula is used to estimate the glomerular filtration rate, while in children it is estimated using the Schwartz formula (2009).

The risk of renal pathology can be increased by:

• kidney trauma;
• urinary infections, pyelonephritis;
• polycystic kidney disease, tuberculosis;
• difficult urination, urethral reflux;
• hereditary predisposition to kidney pathology;
• anomalies of kidney development;
• low birth weight;
• type 1 and type 2 diabetes mellitus;
• heart disease, heart failure, hypertension;
• obesity;
• autoimmune diseases;
• haemolytic anaemia (haemoglobin breakdown products are excreted by the kidneys), malaria;
• HIV infection
• cancer disease
• worms;
• intestinal diseases (dysbacteriosis, constipation, impaired absorption of useful substances in the intestine);
• age over 60 years;
• tobacco smoking.