Kidney function tests 1 Estimation of blood urea

Kidney function tests

• 1. Estimation of blood urea. • 2. Estimation of serum creatinine. • 3. Estimation of serum uric acid.

Estimation of blood urea by Nessler’s reagent • Urea is the main end product of protein (amino acid) metabolism. • Principle: • In this reaction we transform urea by urease enzyme into ammonium carbonate which reacts with Nesslers to from a colored complex.

• Site of urea formation: • 1. Liver is the only site for urea formation. • 2. Then urea is transported in the blood to the kidney to be excreted in urine (its urinary amount is 20 -40 g/day) • Blood urea: is 20 – 50 mg/dl

Diagnostic importance of blood urea: • 1. Measurement of blood urea is one of the kidney function tests. • 2. In kidney diseases as in renal failure, kidney fails to excrete urea, resulting in high blood urea level (may reach up to 400 mg/dl). • 3. In liver diseases, blood urea level decreases, and in turn, ammonia level increases.

• 2 - Estimation of Creatinine level using Jaffe’s reaction utilizing alkaline picrate • Principle: Creatinine complexes with alkaline picrate {Nao. H 0. 75% or ¾ N)+Picric acid} to give an orange –colored complex which is called Jaffe’s reaction. • Creatinine is the waste product of creatine, which the muscles use to make energy depends on the age, gender, and body size. • It is excreted unchanged by the kidneys. • Creatine is synthesized primarily in the liver.

3. Estimation of serum uric acid • Uric acid is the end product of purine metabolism. • Nearly half of the uric acid is eliminated and replaced daily by way of urinary excretion and through microbial degradation in the intestinal tract.

Hyperuricaemia May be observed in : Renal dysfunction Gout leukemia Polycythaemia (abnormally increased concentration of haemoglobin in the blood) • Atherosclerosis: inflammation induces endothelial dysfunction , and stimulate smooth muscle cell proliferation. • Diabetes • Hypothyroidism, or in some genetic diseases. • • •

• Decreased levels are present in: • Wilson’s disease: a genetic disorder in which excess copper builds up in the body. yellowish skin and itchiness. • Bronchogenic carcinoma • Severe hepatocellular disease • Hodgkin’s disease: a type of lymphoma, which is a blood cancer that starts in the lymphatic system. The lymphatic system helps the immune system get rid of waste and fight infections. Hodgkin's lymphoma.