HA Medicine I & Gynecology
UNIT 5: Endocrine System Disorders
Second Year Health Science (PCL) | CTEVT Syllabus (2024)
Introduction to Endocrine Disorders
The endocrine system regulates vital bodily functions through hormones. This unit covers two major endocrine disorders: Diabetes Mellitus and Thyroid Disorders. Understanding these conditions is crucial for health science professionals as they are highly prevalent and require comprehensive management approaches including medication, lifestyle modification, and patient education. – HA Medicine I And Gynecology Unit 5 Endocrine Disorders Notes
5.1 Diabetes Mellitus
Pancreatic islets of Langerhans: Alpha (α), Beta (β), and Delta (δ) cells.
Pancreatic Physiology & Hormone Secretion
Islet Cell Types
- Beta Cells (β): Secrete Insulin → Lowers blood glucose
- Alpha Cells (α): Secrete Glucagon → Raises blood glucose
- Delta Cells (δ): Secrete Somatostatin → Regulates insulin & glucagon
- PP Cells: Secrete Pancreatic Polypeptide → Appetite regulation
Key Mnemonic
“BAGS” for Pancreatic Islet Cells:
Beta → Insulin (Lowers glucose)
Alpha → Glucagon (Raises glucose)
Gamma → (PP cells) Pancreatic Polypeptide
Somatostatin → Delta cells (Inhibits both)
Types, Pathophysiology & Clinical Features
| Feature | Type 1 DM | Type 2 DM |
|---|---|---|
| Onset Age | Usually < 20 years (Juvenile) | Usually > 40 years (Adult) |
| Pathogenesis | Autoimmune β-cell destruction → Absolute insulin deficiency | Insulin resistance + Relative insulin deficiency |
| Classic Symptoms | Polyuria, Polydipsia, Polyphagia, Weight loss (3Ps + Weight loss) | Often asymptomatic or gradual onset of 3Ps, Obesity common |
| Insulin Levels | Low/Absent | Normal/High initially, may become low over time |
Management Strategies
Type 1 DM: Lifelong insulin therapy (Multiple daily injections or insulin pump).
Type 2 DM:
- Lifestyle: Diet control, regular exercise, weight management
- Oral Hypoglycemics: Metformin (first-line), Sulfonylureas, DPP-4 inhibitors, etc.
- Injectable: GLP-1 agonists, Insulin (when oral agents fail)
Acute Complications Comparison
| Feature | DKA | HHS |
|---|---|---|
| Glucose | 250-600 mg/dL | >600 mg/dL |
| Ketones | Present (High) | Absent/Minimal |
| Acidosis | Yes (pH <7.3) | No/Minimal |
| Typical Patient | Type 1 DM | Type 2 DM (Elderly) |
Mnemonic for DKA: “DKA” – Dehydration, Ketonemia, Acidosis.
Chronic Complications
Microvascular
- Retinopathy: Leading cause of blindness
- Nephropathy: Leading cause of ESRD
- Neuropathy: Peripheral & Autonomic
Macrovascular
- Coronary Artery Disease (2-4x risk)
- Cerebrovascular Disease (Stroke)
- Peripheral Arterial Disease
Other
- Diabetic Foot Ulcers
- Infections
- Delayed wound healing
5.2 Thyroid Disorders
Thyroid Hormone Synthesis (5 Steps)
- Iodide Uptake: Active transport of iodide (I⁻) into thyroid follicular cells via NIS (Na⁺/I⁻ symporter).
- Oxidation & Organification: Iodide → Iodine (by TPO enzyme) → binds to tyrosine residues on thyroglobulin → forms MIT & DIT.
- Coupling: TPO mediates coupling of MIT & DIT → T3 (MIT + DIT) and T4 (DIT + DIT).
- Storage: T3 & T4 stored in colloid as part of thyroglobulin.
- Release: Endocytosis → proteolysis → release of T3 & T4 into blood (regulated by TSH).
Mnemonic: “I Owe Cute Squirrels Really” – Iodide uptake, Oxidation, Coupling, Storage, Release.
Hypothyroidism vs Hyperthyroidism
| Aspect | Hypothyroidism | Hyperthyroidism |
|---|---|---|
| Definition | Deficiency of thyroid hormone → ↓ Metabolism | Excess of thyroid hormone → ↑ Metabolism |
| Common Causes | Hashimoto’s, Iodine deficiency, Post-thyroidectomy | Graves’ disease, Toxic nodular goiter, Thyroiditis |
| Key Symptoms | Fatigue, Weight gain, Cold intolerance, Constipation, Dry skin | Weight loss, Heat intolerance, Palpitations, Tremor, Diarrhea |
| Signs | Bradycardia, Myxedema, Hoarse voice, Delayed DTRs | Tachycardia, Exophthalmos (Graves’), Fine tremor, Warm skin |
Diagnostic Investigations
First-line Test: TSH (Thyroid Stimulating Hormone)
- High TSH + Low Free T4: Primary Hypothyroidism
- Low TSH + High Free T4/T3: Primary Hyperthyroidism
Additional Tests:
- Thyroid Antibodies (Anti-TPO, TRAb for Graves’)
- Thyroid Ultrasound (for nodules, size)
- Radioactive Iodine Uptake (RAIU) scan
- FNAC (for suspicious nodules)
Management Approaches
Hypothyroidism
Levothyroxine (T4) – Synthetic thyroid hormone replacement.
- Start low, titrate based on TSH (goal: Normal range)
- Take on empty stomach, 30-60 min before breakfast
- Lifelong therapy for primary hypothyroidism
Hyperthyroidism
- Antithyroid Drugs: Methimazole, PTU (Propylthiouracil)
- Radioactive Iodine (I-131): Destroys thyroid tissue
- Surgery: Thyroidectomy (for large goiters, cancer, pregnancy)
- Symptomatic Control: Beta-blockers for tachycardia
Special Considerations: Pregnancy
- Hypothyroidism: Levothyroxine dose often needs increase (by ~25-30%). Target TSH <2.5 mIU/L in 1st trimester.
- Hyperthyroidism: PTU preferred in 1st trimester (less placental transfer). Methimazole may be used in 2nd/3rd trimester.
- Radioactive iodine is contraindicated in pregnancy and breastfeeding.
- Monitor thyroid function every 4-6 weeks during pregnancy.
Quick Self-Assessment
Test your understanding of key concepts from this unit.
1. Which pancreatic cells secrete insulin and what is their primary function?
2. A patient presents with weight loss, heat intolerance, tachycardia, and exophthalmos. What is the most likely diagnosis?
Unit Summary & Key Points
Diabetes Mellitus
- Type 1: Autoimmune, insulin-dependent, juvenile onset
- Type 2: Insulin resistance, lifestyle-related, adult onset
- Management: Insulin for Type 1; Lifestyle + oral agents ± insulin for Type 2
- Complications: Microvascular (retinopathy, nephropathy, neuropathy) and Macrovascular
Thyroid Disorders
- Hypothyroidism: Slow metabolism, treat with levothyroxine
- Hyperthyroidism: Fast metabolism, treat with antithyroid drugs, RAI, or surgery
- Diagnosis: TSH is first-line test
- Special considerations in pregnancy
Critical Distinctions
- DKA vs HHS: Ketones present in DKA, absent in HHS
- TSH pattern: High in primary hypothyroidism, Low in primary hyperthyroidism
- Graves’ disease: Hyperthyroidism with exophthalmos, TRAb positive
- Hashimoto’s: Hypothyroidism with anti-TPO antibodies
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