Case Presentation: A 31 year old man with a history of spinal muscular dystrophy presented to the emergency department with one day of severe nausea, vomiting, and abdominal pain. The day prior to his presentation, he had undergone a right radical orchiectomy for a scrotal mass. The pathology for the lesion was still pending at the time of presentation. In the ED, a CT of his abdomen and pelvis was obtained, which demonstrated no acute intra-abdominal pathology, and stable post-surgical findings. Urology was consulted, and they attributed his symptoms to administration of sedatives during his procedure. He was subsequently admitted to general medicine for further evaluation and management. Upon reviewing his chemistry, he demonstrated a significant metabolic acidosis with bicarbonate of 11, and elevated anion gap of 18. His creatinine was low at 0.2, and his lactate was within normal range. Per patient history, he had no ingestion of any volatile alcohols or other potentially toxic substances. A urine tox was negative, as well. However, his serum beta-hydroxybutyrate was significantly elevated at 5.6. The patient adamantly denied a personal or family history of diabetes mellitus. He further reported that he had not eaten in two days, as he was instructed to be NPO prior to his procedure. An insulin infusion was started, he was aggressively hydrated with dextrose containing fluid, and his electrolytes were replaced. His anion gap subsequently closed, and his bicarbonate normalized. His A1C and C-peptide came back as negative, and his insulin infusion was discontinued. His symptoms improved shortly after, and he was discharged to home with outpatient follow up.
Discussion: This patient presented with what appeared to be DKA given his elevated serum ketone level. While his serum glucose was normal, DKA is not uncommonly seen in diabetics whose blood sugars are within normal or even low range. However, this patient was not diabetic as seen by his normal A1C and C-peptide. Interestingly, his serum ketone was a result of rapid starvation ketosis in the setting of NPO status prior to a urological surgery. Given his spinal muscular dystrophy, the patient had minimal musculature, which was further suggested by his abnormally low serum creatinine. And thus, he had negligible muscle glycogen storage. In a normal person, approximately 100 grams of glycogen are stored in the liver, and 500 grams are stored in the muscles. Furthermore, a normal person can fast for several days prior to going into ketosis, whereas this patient began ketogenesis in a much shorter time frame and likely in a more rapid rate. Fortunately, his symptoms resolved after administration of a simple sugar such as dextrose, and he was instructed to refrain from prolonged fasting in the future.
Conclusions: Starvation ketosis should be suspected in a patient with an anion gap metabolic acidosis, normal serum glucose, lactate, and renal function. Clinical suspicion should be further heightened in patients with low muscle mass or underlying liver disease.
To cite this abstract:Quin K. Npo at Midnight: A Rare Unintended Consequence. Abstract published at Hospital Medicine 2016, March 6-9, San Diego, Calif. Abstract 744. Journal of Hospital Medicine. 2016; 11 (suppl 1). https://www.shmabstracts.com/abstract/npo-at-midnight-a-rare-unintended-consequence/. Accessed May 21, 2019.