VCP 511: Diagnostic Laboratory Section

PHOSPHORUS

Method of Estimation: Phosphomolybdate method 

Principle

Determination of inorganic phosphorous according to the following reaction.

Reagent composition

• Sulphuric acid    - 210mmol /L
• Ammonium molybdate - 650mmol /L

Laboratory procedure

	Blank	Standard	Sample
Reagent	1000 µL	1000 µL	1000 µL
Standard	--	20 µL	--
Sample	--	--	20µL
Mix and incubate at 37˚C for 1 minute Read the absorbance of standard and sample against reagent blank.

Calculation

Phosphorous conc. (mg /dL) =(Absorbance of Sample  / Absorbance of Standard) x 5

Phosphorous standard concentration = 5 mg / dL

Increased Phosphorus seen in

• Renal disease
• Young age (bone growth)
• Hyperthyroidism
• Hypoparathyroidism
• Renal secondary hyperparathyroidism

Decreased phosphorus seen in

• Hyperparathyroidism
• Hypercalcemia of malignancy
• Neoplasia