Table 1.

Characteristic findings, investigations, and treatment of primary/secondary hyperparathyroidism and distal renal tubular acidosis

Disorder	Suggestive features	Investigations	Treatment
Primary hyperparathyroidism	↑ or ↑N serum calcium	Serum calcium	Treat vitamin D deficiency
	↑ or ↑N serum PTH
	Hypercalciuria	PTH	Referral to endocrinology
	Calcium oxalate or calcium phosphate stone
	↓ Bone mineral density	Vitamin D
Secondary hyperparathyroidism	↑ serum PTH	Serum calcium	Treat vitamin D deficiency
	↓ Vitamin D
	↓ or N serum calcium	PTH	Consider referral to endocrinology
	Hypercalciuria
	↓ Bone mineral density	Vitamin D
Complete distal renal tubular acidosis	Urine pH >5.8	Serum electrolytes	Alkali citrate
	↓ serum bicarbonate
	↓ serum potassium	Urine pH	Thiazide
	Pure apatite stone
	Hypocitraturia	24h urine collection
	Hypercalciuria
	↓ Bone mineral density
Incomplete distal renal tubular acidosis	Urine pH >5.3	Serum electrolytes	Alkali citrate
	↓ N serum bicarbonate
	↓ N serum potassium	Urine pH	Thiazide
	Pure apatite stone
	Hypocitraturia	24h urine collection
	Hypercalciuria

PTH: parathyroid hormone, ↑ = high, ↑N = at the high end of normal range; ↓ = low, ↓N = at the low end of normal range.