Beyond kidney stones: Why pediatricians should worry about hypercalciuria

Table 1 Normal values for random urine and 24 h urine factors for children and adolescents

	24 h urine	Random urine corrected by creatinine				Random urine factored for GFR
Volume	≥ 1.0 mL/kg per h
Creatinina	2 to 3 yr: 6 to 22 mg/kg; > 3 yr: 12 to 30 mg/kg
Calcium	< 4.0 mg/kg (0.10 mmol/kg)	Age		mg/mg; mmol/mmol		< 0.10
		0-6 mo		< 0.80; < 2.24
		6-10 mo		< 0.60; < 1.68
		1-2 yr		< 0.40; < 1.12
		2-18 yr		< 0.21; < 0.56
Citrate	≥ 400 mg/g creatinine	≥ 0.28 (mmol/L/mmol/L)				> 0.18 (mg/L/mg/L)
Calcium/Citrate	< 0.33	< 0.33
Na/K	< 3.5	< 3.5
Uric acid	< 815 mg/1.73m2 BS	< 0.65				< 0.56 mg; < 0.03 mmol
Cystine	< 60 mg/1.73 m2 BS	< 0.02 (mg/mg); < 0.01 (mmol/mmol)
Magnesium	> 88 mg/1.73 m2 BS
Phosphate	TP/GFR1: > 2.8 and < 4.4 mg/dL
Oxalate	< 50 mg/1.73m2 BS; < 0.49 mmol/1.73m2 BS	Age	(mg/mg)
		0-6 mo	< 0.30
		7 mo - 4 yr	< 0.15
		> 4 yr	< 0.10

¹TP/GFR = Pp – (Pu × Crp)/Cru.

GFR: Glomerular filtration rate; TP: Tubular phosphate reabsorption; Pp: Plasma phosphate; Pu: Urinary phosphate; Crp: Plasma creatinine; Cru: Urinary creatinine. Adapted from: Penido MGMG, Tavares MS. Pediatric primary urolithiasis: Symptoms, medical management and prevention strategies. World J Nephrol 2015; 4: 444-454. Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc[2].