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Background: Growth parameters are a powerful screening tool in pediatric care. Accuracy assumes differing importance in different clinical settings. A small error is not clinically significant when height is obtained as a screening tool during annual well child visits. However, when assessing annual growth velocity using shorter interval visits, an error of equal magnitude might influence further management decisions. AIM AND HYPOTHESIS: To explore the effect of inspiration or expiration on height measurement. Our hypothesis was that height measurements obtained in inspiration would be greater than those obtained in expiration or without specific instructions as to status of respiration (unspecified)., Methods: Heights of 99 individuals 8 years and older were measured in inspiration, expiration and unspecified respiratory status by two pediatric endocrinologists. Patients were measured three times in each mode. The p values were adjusted by Tukey procedure for multiple comparisons among three modes., Results: Height measurement performed in inspiration, expiration or without specific instruction as to breathing (unspecified) did affect height measurement. Mean difference +/- SEM (95% CI) between height obtained in inspiration and expiration was 0.22 +/- 0.03 cm (95% CI: 0.15, 0.29); between inspiration and unspecified 0.31 +/- 0.04 cm (95% CI: 0.22, 0.40); and between expiration and unspecified 0.092 +/- 0.03 cm (95% CI: 0.03, 0.16)., Conclusions: Based on these results, we recommend multiple height measurements using uniform technique including inspiratory/expiratory status, especially when calculating 'annualized' height velocity over short intervals.

Traditional methods for treating central diabetes insipidus during infancy, such as fluid therapy or the use of intranasal hormone replacement, have significant potential limitations. In a retrospective study of infants with diabetes insipidus, we examined outcome using subcutaneous (sc) DDAVP, and compared this to infants treated with intranasal lysine vasopressin or DDAVP. After in-patient dosage titration, outpatients' serum sodium concentrations were maintained in a narrower range in the sc group compared with the intranasal group, and the percentage of serum sodium concentrations within the normal range was greater in the sc group. There were no significant complications in either group. We conclude that DDAVP administered subcutaneously can be a safe and effective alternative to traditionally recommended treatments of central diabetes insipidus during infancy.

Thyrotoxic hypokalemic periodic paralysis (THypoKPP) is an uncommon disorder with an unknown etiology. We describe a family in which the proband presented with paralysis and thyrotoxicosis. Because of similarities between familial hypokalemic periodic paralysis (FHypoKPP) and THypoKPP, we sequenced exon 12 of the SCN4A gene, which is known to be mutated in FHypoKPP. We identified an Arg672Ser mutation in the proband and his affected father, as well as the proband's brother. As the brother has paralysis without thyrotoxicosis, our finding suggests that the genetic spectrum of FHypoKPP and THypoKPP overlap. We speculate that thyroid hormone may exert a threshold or permissive effect in hypokalemic periodic paralysis. Non-thyrotoxic family members of individuals with THypoKPP may have an unrecognized risk for paralysis.