Introduction: Starvation ketosis outside pregnancy is a rare phenomenon and is unlikely to cause a severe acidosis. Pregnancy is an insulin resistant state due to placental production of hormones including glucagon and human placental lactogen. Insulin resistance increases with advancing gestation and this confers a susceptibility to ketosis, particularly in the third trimester. Starvation ketoacidosis in pregnancy has been reported and is usually precipitated by a period of severe vomiting. Ketoacidosis has been associated with intrauterine death.
Case report: A 22-year-old woman in her third pregnancy presented at 32 weeks gestation with a 24 h history of severe vomiting. She had been treated for an asthma exacerbation with prednisolone and erythromycin the day prior to presentation. She was unwell, hypertensive (145/70 mmHg) with a sinus tachycardia and Kussmaul breathing. Urinalysis showed ++++ ketones, + protein and pH 5. Fingerprick glucose was 4 mmol/l and ketones were 4.0 mmol/l. Arterial blood gas showed pH 7.27, PaCO2 1.1 kPa, base excess −23, bicarbonate 8.6 mmol/l and lactate 0.6 mmol/l. The anion gap was 20. Serum ethanol, salicylates and paracetamol levels were undetectable. She was fluid resuscitated but her biochemical parameters did not improve. She was intubated and underwent emergency caesarean section. A healthy boy was delivered and her acidosis resolved over the subsequent 8 h.
Discussion: We believe this case is explained by starvation ketoacidosis. There was no evidence of diabetes mellitus or other causes of a metabolic acidosis. In view of the hypertension, proteinuria and raised urate the differential diagnosis was an atypical presentation of pre-eclampsia.
This case illustrates the metabolic stress imposed by the feto-placental unit. It also highlights the importance of regular meals in pregnancy and sufficient calorific intake in patients who are vomiting, as well as the need for cautious prescribing of medications, which may worsen the insulin resistant state.