Makindo Medical Notes

🧑‍⚕️ Case Examples — Polyuria & Polydipsia

• Case 1 (Type 1 Diabetes Mellitus): 🍬 A 17-year-old boy presents with 4 weeks of thirst, polyuria, and weight loss. He is fatigued and has new nocturia. Random glucose is 22 mmol/L and ketones are positive. Diagnosis: Newly diagnosed type 1 diabetes. Teaching point: Classic osmotic symptoms in a young patient → always check glucose and ketones; urgent insulin initiation is required.
• Case 2 (Type 2 Diabetes Mellitus): 📈 A 55-year-old overweight woman presents with several months of increasing thirst and urination, particularly at night. Fasting glucose is 12 mmol/L and HbA1c is 64 mmol/mol. Diagnosis: Type 2 diabetes. Teaching point: Gradual onset of osmotic symptoms in middle age, often with metabolic syndrome features; managed with lifestyle modification ± metformin.
• Case 3 (Diabetes Insipidus — Central): 💧 A 30-year-old man reports extreme thirst and passing >6 L of dilute urine daily. Serum sodium is high at 152 mmol/L, plasma osmolality raised, urine osmolality very low. Water deprivation test shows no concentration; desmopressin corrects it. Diagnosis: Central diabetes insipidus. Teaching point: Failure to secrete ADH → polyuria + polydipsia with hypernatraemia; responds to desmopressin.
• Case 4 (Diabetes Insipidus — Nephrogenic): 🧪 A 65-year-old man on long-term lithium presents with thirst and polyuria. Labs show high plasma osmolality, low urine osmolality, and no response to desmopressin during water deprivation test. Diagnosis: Nephrogenic diabetes insipidus (lithium-induced). Teaching point: Kidneys fail to respond to ADH; treatment includes stopping offending drug and considering thiazides or amiloride.
• Case 5 (Primary Polydipsia): 🚰 A 28-year-old woman with anxiety presents with passing >5 L urine/day. Labs show low-normal sodium and very dilute urine. Water deprivation test shows gradual rise in urine osmolality. Diagnosis: Primary psychogenic polydipsia. Teaching point: Distinguished from DI by normal ADH axis; behaviourally driven excessive fluid intake → hyponatraemia risk.