Endocrine & Renal Pathology — Must Know Notes

## Summary ## Summary This document provides concise, essential notes on endocrine and renal pathology, covering key diseases, their causes, clinical presentations, diagnostic methods, and treatment approaches. It emphasizes critical differences between related conditions, such as primary versus secondary adrenal insufficiency, and outlines the pathophysiology and management of diabetes mellitus, parathyroid disorders, and renal pathologies like acute kidney injury and chronic kidney disease. The notes also touch upon lung tumours and lung transplantation, highlighting their crucial aspects for medical understanding. ## Key Points - ## Summary This document provides concise, essential notes on endocrine and renal pathology, covering key diseases, their causes, clinical presentations, diagnostic methods, and treatment approaches. - It emphasizes critical differences between related conditions, such as primary versus secondary adrenal insufficiency, and outlines the pathophysiology and management of diabetes mellitus, parathyroid disorders, and renal pathologies like acute kidney injury and chronic kidney disease. - The notes also touch upon lung tumours and lung transplantation, highlighting their crucial aspects for medical understanding. - ## Key Points - **Adrenal Insufficiency (Addison's Disease):** Inadequate cortisol ± aldosterone production due to primary (autoimmune, TB) or secondary (steroid use, pituitary issues) causes. - Primary leads to hyperpigmentation and electrolyte imbalances due to ↑ACTH, while secondary does not cause hyperpigmentation and has intact aldosterone. - - **Cushing's Syndrome:** Chronic excess cortisol from exogenous steroids (most common) or endogenous causes like pituitary ACTH adenoma (Cushing's disease), ectopic ACTH, or adrenal tumours. - Presents with characteristic central obesity, moon face, and metabolic disturbances. - - **Hyperaldosteronism (Conn's Syndrome):** Excess aldosterone leading to hypertension and hypokalaemia. ## Detailed Notes ## Key Points - **Adrenal Insufficiency (Addison's Disease):** Inadequate cortisol ± aldosterone production due to primary (autoimmune, TB) or secondary (steroid use, pituitary issues) causes. Primary leads to hyperpigmentation and electrolyte imbalances due to ↑ACTH, while secondary does not cause hyperpigmentation and has intact aldosterone. - **Cushing's Syndrome:** Chronic excess cortisol from exogenous steroids (most common) or endogenous causes like pituitary ACTH adenoma (Cushing's disease), ectopic ACTH, or adrenal tumours. Presents with characteristic central obesity, moon face, and metabolic disturbances. - **Hyperaldosteronism (Conn's Syndrome):** Excess aldosterone leading to hypertension and hypokalaemia. Primary (adenoma/hyperplasia) shows suppressed renin, while secondary has elevated renin. - **Phaeochromocytoma:** Catecholamine-secreting tumour of the adrenal medulla, causing paroxysmal hypertension, palpitations, and sweating. - **Diabetes Mellitus:** Type 1 (autoimmune β-cell destruction, absolute insulin deficiency) and Type 2 (insulin resistance, relative deficiency). Diagnosis via glucose levels or HbA1c. DKA (Type 1) and HHS (Type 2) are acute complications. - **Parathyroid Disorders:** Primary hyperparathyroidism (autonomous PTH overproduction) causes ↑Ca²⁺, ↓phosphate. Secondary (renal failure) causes compensatory ↑PTH. Hypoparathyroidism leads to ↓Ca²⁺, ↑phosphate. - **Porphyrias:** Enzyme defects in haem biosynthesis. Acute porphyrias are neurovisceral, while cutaneous porphyrias cause photosensitivity. Triggers are crucial. - **Renal Function Evaluation:** GFR is the best marker. BUN:Creatinine ratio, FENa, and urine casts are vital for diagnosing AKI and understanding intrinsic renal disease. - **Acute Kidney Injury (AKI):** Rapid decline in renal function (creatinine rise, ↓ urine output). Classified as prerenal (↓ perfusion), intrinsic (ATN, AIN, GN), or postrenal (obstruction). - **Chronic Kidney Disease (CK D):** Progressive loss of renal function (eGFR <60). Causes include diabetes and hypertension. Complications include anaemia, secondary hyperparathyroidism, and cardiovascular disease. - **Renal Calculi:** Stones formed in the urinary tract. Types include calcium oxalate, uric acid, struvite, and cystine. Clinical features include colic and haematuria. - **Lung Tumours:** Primarily carcinomas (adenocarcinoma, squamous cell, small cell, large cell). Smoking is the main risk factor. Small cell lung cancer is aggressive and metastatic at diagnosis. - **Lung Transplantation:** For end-stage lung disease. Complications include infections, acute rejection, and chronic rejection (bronchiolitis obliterans). ## Detailed Notes ### 1. ADRENAL INSUFFICIENCY (ADDISON'S DISEASE) **Definition:** Inadequate cortisol ± aldosterone production. **Primary causes:** Autoimmune (most common in developed world), TB (most common in developing world), Waterhouse-Friderichsen syndrome (meningococcal sepsis leadin