Phosphate (as Phosphorus)

Serum phosphorus (Phosphate) levels are of limited diagnostic value and should be correlated with serum calcium levels. Increased phosphorus with decreased calcium suggests either hypoparathyroidism or renal disease. Reduced phosphorus and increased calcium suggest hyperparathyroidism or sarcoidosis. When calcium and phosphorus are decreased, diagnostic considerations include malabsorption, vitamin D deficiency, and renal tubular acidosis. Increased phosphorus and normal or high calcium suggest Milk-alkali syndrome or hypervitaminosis D.