Thyroid and adrenal factors in hyaline membrane disease

Bilateral cervical vagotomy (BCV) in newborn rabbits is a known model for hyaline membrane disease (HMD) of premature human newborns. The survival curve of animals kept in air is triphasic, a semi‐log plot, a steep slope to 9h, then −0.136 to 67 hours, and −0.476 terminally [Exp.Mol.Pathol. 2010, 89, 36]. Mean gross lung change, by pleural surface measurement, was 3.95±0.89% in phase A (p<0.001) and 35.82±9.34 and 37.0±12.74 (n.s.), in phases B‐C. Pre‐BCV thyroxine at 1, 10, 100 mg/kg at 3 h modifies the outcome in various ways: [1] maximal survivals were 0.76, 0.66, and 0.76 of control, [2] extent of lung change phase A increased to means of 8.33, 20.77, and 25.7% respectively with no significant change occurred in phase B or C.. By contrast 1 unit/kg thyrotropin produced phase A lung injury similar to BCV‐air controls but more than doubled the effect in phases B (73%) and C(72%). Archival human autopsy data, (450 cases, 154 HMD and 296 without), reveals consistent undergrowth of the thyroid and the adrenals in HMD. When normalized against the maximal gland weights in the 37–39 week non‐HMD group (N= 81), both adrenals and thyroids in HMD cases had mean weights at 0.562 of the standard controls; at 34–36 weeks the ratio for thyroids was 0.434, for adrenals, 0.595. Lower values for HMD were seen over the gestational span from 25–39 weeks, with near linear progression; the non‐HMD values accelerated from 31 to 35 weeks. John A Hartford Fdn.