Basic Concepts in Clinical Biochemistry-A Practical Guide.7z

Na 2 CO 3 (ml) 1 1 1 1 1 1 1 1 1

Phosphotungstic acid (ml) 1 1 1 1 1 1 1 1 1

Mix well and keep for 20 min at room temperature, read absorbance at 700 nm

20.6 Calculations

Plot a graph between amount of uric acid at x-axis and absorbance at y-axis and
extrapolate uric acid concentration of given sample from the graph. The uric acid
concentration can also be calculated by using equation:

Uric acid amount in urine¼

ODof testamount of standardðÞμg 100

ODof standardvolume of sample 1000

¼xmg=dl

Uric acid amount in urine

¼

OD of testamount of standardðÞμg dilution factor 1000

OD of standardvolume of sample 1000

¼xmg=L

Note 3 ml of protein-freefiltrate is equivalent to 0.3 ml serum/urine sample since
0.5 ml sample was made to total 5 ml before preparing protein-freefiltrate.

20.7 Clinical Significance...............................

Uric acid levels in serum range from 3.5–8 mg/dl in males and 2.0–6.5 mg/dl in
females. Normal uric acid excretion through urine depends upon diet. A purine-rich
diet and severe exercise increase uric acid levels. Estimation of uric acid in serum is
helpful in the diagnosis of several pathological conditions particularly gout where
increased uric acid levels up to 6.5–12 mg/dl is observed. Gout is the most common
disease that increases uric acid levels in serum. It is disease of joints in which uric
acid is deposited as crystals. Increased uric acid in blood is generally accompanied
by increased excretion in urine. Other disease conditions such as renal failure,
leukemia, multiple myeloma, lymphoma, glycogenesis, chronic hemolytic anemia,
and pernicious anemia lymphosarcoma also increase serum uric acid levels. Serum
uric acid levels less than 2 mg/dl cause hypouricemia. It is caused due to severe
hepatocellular disease and defective renal tubular reabsorption of uric acid. Low
values may be also found in Wilson’s disease. Several drugs affect the handling of
urate by the body. Urinary decrease in uric acid levels is observed in xanthinuria,
folic acid deficiency, or lead toxicity.

20.7 Clinical Significance 83