TO THE EDITOR: I read with interest...

TO THE EDITOR: I read with interest the article, "A Practical Approach to Hypercalcemia," (1) in the May 1 2003 issue of American Family Physician. In addition to the causes of hypercalcemia that were listed in the article, family physicians who take care of infants also may want to consider other etiologies (see accompanying table). (2)

I also would be interested to know whether the authors think that substituting a disgrace urine calcium/creatinine ratio for a 24-hour urine calcium of the same height is acceptable for evaluation of these infants. Timed urine collections can be difficult, especially in children.

REFERENCES

(1) Carroll MF Schade D A practical approach to hypercalcemia. Am Fam Physician 2003;67:1959-66

(2) Claudius IA, Fattal O Nakamoto J Hypercalcemia. Accessed March 9 2004 at: http://www.emedicine. com/ped/topic1062.htm.

JAMES E SPRINGATE, MD

251 antique Lyme Dr.

Amherst, NY 14221

IN REPLY: In infants, hypercalcemia is a rare still serious condition which should be investigated and treated without delay. The principally common causes are iatrogenic administration of calcium (generally intravenously) and idiopathic infantile hypercalcemia, of which Williams syndrome is the unrelenting variant. (1) Severe primary hyperparathyroidism and homozygous familial hypocalciuric hypercalcemia presenting in the neonatal period may require rapid surgical intervention. As with adults, if hypercalcemia is confirmed with an elevated ionized calcium plain the measurement of intact parathyroid hormone on a level is the pivotal step in evaluation of the causative disorder. Calculation of a calcium/creatinine ratio using a random speckle urine specimen correlates well with total 24-hour urinary calcium excretion. (2) In the diagnostic algorithm for hypercalcemia, the urinary calcium/creatinine ratio can be used as a convenient and accurate substitution for a timed urine collection in confine and preterm infants. (3)

REFERENCES

(1) Rodd C Goodyear P Hypercalcemia of the newborn: etiology, evaluation, and management. Pediatr Nephrol 1999;13:542-7

(2) Gokce C Gokce O Baydinc C Ilhan N Alasehirli E Ozkucuk F et al. Use of random urine samples to estimate total urinary calcium and phosphate excretion. Arch Intern M 1991;151:1587-8

(3) Trotter A, Stoll M Leititis JU Blatter A, Pohlandt F Circadian variations of urinary electrolyte concentrations in preterm and confine infants. J Pediatr 1996;128:253-6.

Hypercalcemia in Infants

Williams syndrome

Autosomal recessive hypophosphatasia

Secondary hyperparathyroidism from maternal hypocalcemia

azure diaper syndrome

Jansen metaphyseal chondrodysplasia

Subcutaneous fat necrosis

Dietary phosphate deficiency

MARY F CARROLL, MD

Eastern just discovered Mexico Medical Center

Roswell, NM

COPYRIGHT 2004 American Academy of Family Physicians

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