Endocrine Abstracts

Background: Hypothyroidism is reported to be associated with mild insulin resistance though severe insulin resistance is rare. We report the case of a man presented with reversible severe insulin resistance in hypothyroidism.

Case report: A 23-year-old obese man with autism was presented with poor responsiveness (GCS 7/15). He had general malaise for 2 days prior to admission. On admission, his test results showed random glucose – 60.8 mmol/l, potassium – 8.0 mmol/l, arterial blood pH – 6.78, bicarbonate – 5.0 mmol/l and 3+ urine ketones. He was managed in ITU as diabetic ketoacidosis and referred to endocrine team on 5th day due to higher insulin requirement (984 units/day).

Investigations: Free T₄ – 4.6 pmol/l (10.0–20.0), Free T₃ – 1.7 pmol/l (3.5–6.5), TSH – 32.69 mIU/l (0.20–6.0), FSH – 0.4 IU/l (1.0–11.0), LH – 0.1 IU/l (1.0–11.0), Testosterone – 0.4 nmol/l (8.0 – 34.0), Prolactin – 1710 mIU/l (0–400), C-peptide – 1348 pmol/l (190–990), GAD antibodies 15.4 nmol/l, random cortisol – 199 nmol/l (120–620), Subsequent short synacthen test and dexamethazone suppression test were normal.

Management: Patient was commenced on levothyroxine. Once hypothyroidism was corrected, his insulin requirement progressively reduced and insulin was stopped on 39th day.

Follow up: Recent HbA1c without any diabetic treatment for 4 months was 4.8%. Serum gonadotrophins, testosterone and prolactin levels normalised. His fasting insulin and C-peptide levels are 175 and 1580 pmol/l respectively.

Discussion: Our patient presented with diabetic ketoacidosis and had severe insulin resistance due to hypothyroidism compounded by obesity and acute illness. His diabetes mellitus fully resolved in subsequent follow up. Hyperprolactinaemia was secondary to hypothyroidism. Gonadotrophin abnormality (sick eugonadal syndrome) can be explained with acute illness.