Bone Health ECHO Case Report: Rare Cases of Hypophosphatemia and Low-Traumatic Fractures in Patients with Type 1 Diabetes Mellitus

Bone Health ECHO (Extension of Community Healthcare Outcomes) is a virtual community of practice that has been connecting healthcare professionals online once weekly for the past 10 years. A key component of each ECHO session is presentation and discussion of patient cases with diagnostic and treatment dilemmas. Here we present two wheelchair-bound female patients aged 47 years (Patient 1) and 34 years (Patient 2), both with type 1 diabetes mellitus (T1DM). They were admitted to our hospital due to multiple fractures and muscle weakness. Since age 8 years, both women suffered from T1DM. Patient 1 had extremely poor glycemic control over the whole period of diabetes with frequent cases of ketoacidosis (glycated hemoglobin [HbA1c] varied 10.0-14.2 %), with multiple end-stage complications of DM including anuria requiring hemodialysis from age 37 years. Patient 2 had minimal DM complications and maintained HbA1c within an individual goal (5.0-6.1 %). Both patients had low fasting phosphate and elevated alkaline phosphatase on laboratory evaluation. In the patient with anuria (Patient 1), after careful evaluation of all possible causes of hypophosphatemia, we found the most likely cause to be the effects of constantly repeated intracellular phosphate depletion due to poorly compensated T1DM. While achieving stable glucose control in hospital care, her phosphate levels gradually returned within the reference range. In the younger patient (Patient 2), tumor-induced osteomalacia (TIO) was diagnosed. After tumor removal her symptoms and laboratory results normalized. These cases illustrate two different causes of hypophosphatemia in patients with similar skeletal presentations in association with T1DM.