Endocrinology II — Diabetes, Calcium, Potassium and Thyroid

Diabetes diagnosis and phenotype

• Diagnose diabetes in nonpregnant adults with HbA1c ≥6.5%, fasting glucose ≥126 mg/dL, 2-hour OGTT ≥200 mg/dL, or symptomatic random glucose ≥200 mg/dL; confirm if asymptomatic.
• HbA1c may mislead with altered red-cell lifespan, transfusion or blood loss, haemoglobin variants, pregnancy, advanced CKD and assay interference.
• Atypical adult diabetes: revisit phenotype with tempo, ketosis, islet antibodies, contextual C-peptide, family pattern, pancreatic disease and drug history.
• Type 1 diabetes always needs basal insulin. Never stop it completely during illness or fasting.
• Asian ancestry lowers risk-based screening BMI threshold to 23 kg/m².

Diabetes treatment and emergencies

• Type 2 therapy is comorbidity-led: SGLT2 inhibitor for HF/CKD when appropriate; GLP-1-based therapy for ASCVD or weight priorities; metformin is useful but not a gatekeeper.
• DKA = diabetes or hyperglycaemia + beta-hydroxybutyrate ≥3 mmol/L or urine ketones ≥2+ + pH <7.3 and/or bicarbonate <18.
• HHS = glucose ≥600 mg/dL + hyperosmolality + beta-hydroxybutyrate <3 + pH ≥7.3 and bicarbonate ≥15.
• DKA with K <3.5 mmol/L: replace potassium first and delay insulin. Add dextrose when glucose <250 while continuing insulin until ketones and acidosis resolve.
• Hypoglycaemia: <70 alert, <54 clinically significant, severe = assistance required. Treat conscious patients with 15 g glucose and recheck in 15 minutes.

Mineral and potassium anchors

• Hypercalcaemia: confirm, then PTH. Non-suppressed PTH during hypercalcaemia is abnormal.
• PHPT surgery: symptoms or Ca >1 mg/dL above ULN, skeletal criterion, renal criterion, sex-specific hypercalciuria or age <50.
• Symptomatic hypocalcaemia: IV calcium gluconate with ECG monitoring, correct magnesium and cause.
• Hypokalaemia: determine shift versus loss; blood pressure plus acid-base state localizes. Never IV-push potassium.
• Hyperkalaemia: ECG calcium → insulin/glucose ± beta-agonist → remove potassium → repeat K, ECG and glucose.

Thyroid anchors

• Primary hypothyroidism: high TSH with low FT4. Central hypothyroidism: low FT4 with inappropriate low/normal TSH; assess cortisol first.
• Graves disease has TRAb/high uptake; thyroiditis has low uptake and does not benefit from thionamide.
• Methimazole/carbimazole is usually preferred in nonpregnant adults; PTU is preferred in first trimester and thyroid storm.
• Fever or sore throat on antithyroid drugs means stop and urgent CBC.
• Thyroid storm: ICU, cooling, safe beta blockade, thionamide, iodine at least 1 hour later, steroid and trigger control.
• Myxoedema coma: ventilation/support, hydrocortisone before or with IV thyroid hormone, cautious passive rewarming and trigger treatment.

High-yield comparison tables

Pharmacology safety round-up

Emergency one-page sequence

• Altered diabetic patient: bedside glucose → airway/circulation → if low, treat immediately → if high, check ketones, gas, electrolytes and osmolality → classify DKA/HHS/other → fluids plus potassium-directed insulin → find trigger → biochemical resolution plus safe transition.
• Weak or paralysed patient with abnormal potassium: ECG and repeat sample → if hyperkalaemic ECG toxicity, calcium first → insulin/glucose plus adjunct → remove potassium → repeat K/glucose/ECG. If hypokalaemic, correct magnesium and potassium with monitoring → determine shift versus renal/GI loss.
• Confused patient with thyroid disease: temperature, heart rate, ventilation, sodium/glucose/cortisol and trigger → storm phenotype: beta blockade only if haemodynamically safe, thionamide, delayed iodine, steroid → myxoedema phenotype: ventilation, steroid first, IV thyroid hormone, passive rewarming.