Changes in serum phosphate during treatment of diabetic ketoacidosis: predictive significance of severity of acidosis on presentation

Abstract

Changes in serum phosphate during diabetic ketoacidosis (DKA) treatment are not well characterised, although it is known that serum phosphate falls with treatment. We sought to define the nature of these changes and whether the severity of acidosis on admission influenced the severity of subsequent hypophosphataemia. We retrospectively reviewed data on all patients with confirmed DKA presenting to our unit between 2007 and 2010 inclusive. Forty-three patients with 64 episodes of DKA were evaluated. At presentation, 62.5% of patient episodes were hyperphosphataemic. Initial serum phosphate in all patient episodes correlated significantly with the initial serum creatinine (r = 0.694, P < 0.01) and the initial blood glucose (r = 0.593, P < 0.01). Serum phosphate fell during the course of treatment in all episodes (mean absolute fall 1.28 ± 0.77 (SEM) mmol/L). The mean nadir phosphate was 0.58 ± 0.19 mmol/L. Ninety per cent of nadir phosphate levels were hypophosphataemic (<0.8 mmol/L), and 11% were severely hypophosphataemic (<0.32 mmol/L). Mean initial bicarbonate differed significantly between those with nadir phosphates <0.5 mmol/L (9.26 ± 4.55) and those with nadir phosphates >0.5 mmol/L (13.0 ± 4.59, P = 0.0031). Similar significant bicarbonate differences were noted between those with nadir phosphates less than and more than 0.32 mmol/L respectively (7.42 ± 2.44 and 12.2 ± 4.87, P < 0.01). The initial hyperphosphataemia is reflective of intravascular volume depletion and pre-renal renal impairment. The severity of subsequent hypophosphataemia can be predicted by the degree of metabolic acidosis on presentation. As profound hypophosphataemia can be associated with serious complications, clinicians should recognise the likelihood of this biochemical derangement in those DKA patients presenting with profound acidosis.

Supraventricular tachycardia as a complication of severe diabetic ketoacidosis in an adolescent with new-onset type 1 diabetes

“…Phosphate serum levels subsequently drop profoundly as a consequence of insulin administration 28. The greater the initial acidosis, the greater the subsequent hypophosphataemia 28. Our patient’s profound serum hypophosphataemia suggests an even greater total body phosphate depletion.…”

“…This is due to a combination of phosphate shifting across the cell membrane from the intracellular to the extracellular and severe hyperphosphaturia 26 27. Phosphate serum levels subsequently drop profoundly as a consequence of insulin administration 28. The greater the initial acidosis, the greater the subsequent hypophosphataemia 28.…”

Retrospective comparison of early‐ versus late‐insulin therapy regarding effect on time to resolution of diabetic ketosis and ketoacidosis in dogs and cats: 60 cases (2003–2013)

“…Electrolyte derangements have been documented to occur frequently pretreatment and with implementation of fluid and insulin therapy in DK/DKA patients . The mechanism of hypokalemia, hypophosphatemia, and hypomagnesemia due to insulin therapy should be independent of the timing of insulin administration, though derangements may be less likely or less severe in patients receiving supplementation for a longer period before starting insulin.…”

Management of adult diabetic ketoacidosis

“…Insulin therapy during DKA will further lower serum phosphate concentration; 90% of patients were shown to have developed hypophosphatemia during infusion of insulin and fluids 22. Prospective randomized studies have failed to show any beneficial effect of phosphate replacement on the clinical outcomes in DKA.…”