Endocrine Abstracts

A 27 years old primigravid lady presented with nausea and recurrent vomiting at 35 weeks gestation. She was diagnosed with hyperemesis gravidarum at 5 weeks gestation. TPN was commenced but she continued vomiting. On examination, foetal size was normal for gestational age, BP was 105/70 mmHg. Electrolytes were normal except potassium of 2.7 mmol/l, LFT was normal, albumin 29 g/l and uric acid 307 umol/l. 16 days after admission, she rapidly deteriorated with weakness and plasma sodium rose from 137 to 187mmol/l in 2 days. She was transferred to ICU. Further investigations revealed rise in AST (124U/l) and ALT (87U/l) and uric acid (557 umol/l). Acid base balance was deranged with pH 7.16, pCO2 8.2 kPa, pO2 28.5 kPa, and bicarbonate 21.4 suggesting mixed respiratory and metabolic acidosis. Serum osmolality was 381mOsm/l and corresponding urinary osmolality was 142 mOsm/l which was suggestive of diabetes insipidus. Emergency Caesarean section was performed due to foetal distress. Sadly, the baby died on day 3 after cardiac arrest. The patient's sodium was gradually reduced from 192 to 144 mmol/l over 5 days with hourly electrolyte monitoring. However, she developed nystagmus on day 3 in ITU and later developed dysmetria, left heel shin ataxia and tandem gait ataxia. MRI brain showed changes consistent with myelinolysis of pons and cerebellar peduncles. Water deprivation test on days 12 and 17 post partum failed to concentrate serum osmolality beyond 290mOsm/l but urinary osmolality rose to 470 and 585mOsm/l respectively excluding diabetes insipidus at that stage.

Summary: this 27 years old lady had hyperemesis gravidarum which was complicated by transient diabetes insipidus of pregnancy with rapid onset hypernatremia which resulted in central pontine myelinolysis, and baby's death.

Conclusion: Gestational diabetes insipidus, a rare condition, when combined with hyperemesis gravidarum can lead to significant morbidity and mortality due to sudden shift in plasma sodium.