DKA and phosphate

Q: 20 years old female with similar prior presentations, admitted to ICU with severe Diabetes Ketoacidosis (DKA). In acute severe presentation of DKA the serum phosphate concentration expected to be? - select one 

A) high

B) low

Answer: A

Both potassium and phosphate throw curveballs in DKA. Though whole-body potassium and phosphate depletion occur in DKA, the initial serum potassium and phosphate concentrations may be normal or elevated on presentation due to their movement out of the cells. Hypokalemia and hypophosphatemia get rapidly unmasked with insulin and intravenous fluid resuscitation.

Said that, unlike potassium, phosphate replacement is not recommended in DKA as phosphate replacement may lead to hypocalcemia and hypomagnesemia unless the level is too low, like below 1 mg/dL or 0.32 mmol/L) or clinical abnormalities of hypophosphatemia are expected, such as cardiac dysfunction, hemolytic anemia, and respiratory depression. In such cases, a combo of potassium and phosphate (potassium-phosphate) can be given.

#endocrinology

References:

1. Kebler R, McDonald FD, Cadnapaphornchai P. Dynamic changes in serum phosphorus levels in diabetic ketoacidosis. Am J Med 1985; 79:571.

2. Zipf WB, Bacon GE, Spencer ML, et al. Hypocalcemia, hypomagnesemia, and transient hypoparathyroidism during therapy with potassium phosphate in diabetic ketoacidosis. Diabetes Care 1979; 2:265.

3. van der Vaart A, Waanders F, van Beek AP, Vriesendorp TM, Wolffenbutel BHR, van Dijk PR. Incidence and determinants of hypophosphatemia in diabetic ketoacidosis: an observational study. BMJ Open Diabetes Res Care. 2021 Feb;9(1):e002018. doi: 10.1136/bmjdrc-2020-002018. PMID: 33597187; PMCID: PMC7893606.

4. Choi HS, Kwon A, Chae HW, Suh J, Kim DH, Kim HS. Respiratory failure in a diabetic ketoacidosis patient with severe hypophosphatemia. Ann Pediatr Endocrinol Metab. 2018 Jun;23(2):103-106. doi: 10.6065/apem.2018.23.2.103. Epub 2018 Jun 20. PMID: 29969883; PMCID: PMC6057019.