Phosphorus amount in urine
¼OD of testamount of standardðÞμg dilution factor 1000
OD of standardvolume of sample 1000 ∗ 1000 ∗¼xg=L*To convertμg to gram
22.9 Clinical Significance...............................
Normal value of serum inorganic phosphorus is 3.0–4.5 mg/dl in adults and is
3 – 5.5 mg/dl in children. Normal range for urine sample is 0.5–1.5 g/24 h. Increase
in an inorganic phosphorus amount is observed in acute and chronic renal failure,
hypoparathyroidism, cell lysis, respiratory acidosis, untreated diabetes, ketoacidosis,
increased phosphate intake, use of phosphate containing laxative and decreased renal
phosphate exertion due to decreased GFR, and increased tubular reabsorption or
acromegaly. The decrease in inorganic phosphorus levels occurs in rickets
(in osteomalacia the phosphorus levels are lower than rickets), lowered renal phos-
phate threshold, decrease in intestinal phosphate absorption due to increased loss in
vomiting, diarrhea, the use of phosphate-binding antacid, vitamin D deficiency, and
in intracellular phosphate loss due to acidosis–ketoacidosis and lactoacidosis.
22.10 Precautions
- All the glasswares used for the estimation and preparation of reagents should be
dipped in HNO 3 (5 N) for 24 h and washed thoroughly in distilled water. - Urine should be preserved in acidic conditions by adding 10 ml HCl to 24 h urine
collection. In alkaline condition the phosphates tends to precipitate. - Collect blood without hemolysis and separate serum immediately after it is
formed.
92 22 Estimation of Inorganic Phosphorus in Serum and Urine