Case Presentation: A 40-year-old previously healthy female presented nine weeks postpartum with numerous episodes of nonbilious, nonbloody emesis that began 24 hours prior to admission. She took no medications and denied fevers, chills, dysuria, cough, or ingestion of alcohol or other substances. She reported that since her uncomplicated vaginal birth, she had been adhering to a strict Paleolithic (low-carbohydrate) diet with an associated 20-pound weight loss. She had continued breastfeeding her 2-year-old child and her newborn. Vital signs on admission were notable for a temperature of 36.5°C, blood pressure of 149/90, heart rate of 118, respiratory rate of 24, and oxygen saturation of 98% on room air. Her BMI was 21. Physical exam revealed a thin, uncomfortable-appearing woman with tachypnea and mild lower-abdominal tenderness. The remainder of the exam was unremarkable.
An initial venous blood gas was notable for pH 6.94, PCO2 25 mmHg and lactate 2.9 mmol/L. Serum bicarbonate was 10 mmol/L with an anion gap of 25 and a glucose of 188 mg/dL. Beta-human chorionic gonadotropin was negative, beta hydroxybutyrate was 15.6 mmol/L, and serum osmolarity was 325 mmol/kg. Osmolal gap was >30. A computed tomography scan of the abdomen and pelvis was unremarkable.
The patient was volume resuscitated and admitted to the intensive care unit. Intravenous glucose-containing fluids, bicarbonate, fomepizole, and thiamine were administered. Over the next day, the anion and osmolal gap closed, pH normalized and her symptoms improved rapidly. Serum ethanol, ethylene glycol, isopropanol, methanol, and aspirin levels were undetectable. Hemoglobin A1C was 5.4 mg/dL and insulin c-peptide was 5.6 ng/mL.

Discussion: In this case, a healthy, non-diabetic woman developed severe ketoacidosis with an osmolal gap in the setting of a strict, low-carbohydrate diet while exclusively breastfeeding two children, consistent with starvation ketoacidosis.
The differential diagnosis and initial management of anion-gap ketoacidosis in the absence of hyperglycemia can be challenging. The presence of an osmolal gap suggests possible alcohol or other toxic ingestion, and thus fomepizole was started empirically on admission and stopped when the patient rapidly improved. Acetone accumulation from starvation can also result in an osmolal gap. Starvation ketoacidosis may occur in healthy adults in the setting of either increased metabolic demand or decreased intake of carbohydrates, both of which were present in this case.

Conclusions: To our knowledge, this is the most severe reported case of starvation ketoacidosis in a lactating woman on a low-carbohydrate diet. Despite the popularity of low-carbohydrate diet plans, the risks are poorly understood. As demonstrated in our case, low-carbohydrate diets can be dangerous, particularly for women who are pregnant or lactating, and physicians must be aware of the presentation of severe starvation ketoacidosis.