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Download MBBS Endocrine Lecture Notes

Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Endocrine 1st Year Handwritten Notes, 2nd Year Handwritten Notes, 3rd Year Handwritten Notes & Final Year Handwritten Notes (Lecture Notes)

This post was last modified on 24 July 2021

MBBS Lecture Notes for all subjects (updated for 2021 syllabus) - All universities




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Hypoglycemia (1)

  • Glucose is the sole energy source for the brain
  • Symptoms of hypoglycemia depend on the glucose level and the rate of glucose drop
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  • Hypoglycemia can mimic stroke, TIA, epilepsy, MS, psychosis, Stokes-Adams
  • Counterregulatory hormones (glucagon and epinephrine) cause the release of glycogen from the liver
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Hypoglycemia (2)

  • Sympathomimetic symptoms: sweating, tremor, pallor (vasoconstriction), anxiety, nausea
  • Sympathomimetic symptoms can be masked by beta blockers
  • Neuroglycopenia symptoms: dizziness, psychosis, confusion, coma

Always consider hypoglycemia in an unresponsive patient – check a rapid blood glucose level

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Hypoglycemia (3)

  • Differential diagnosis
    • Insulinoma
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    • Medications / drugs / alcohol
    • Extrapancreatic neoplasm
    • Hepatic disease (depletion of glycogen stores)
    • Deficiency of counterregulatory hormones
    • Critically ill, stressed infants, hypothermia
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    • Dumping syndrome
  • Artifactual
    • Continued glycolysis by WBCs in lab tube
    • Leukemia, polycythemia
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Hypoglycemia (4)

  • Distinguishing excess endogenous insulin from excess exogenous insulin
    • Pancreas cleaves proinsulin to insulin plus immunoreactive C-peptide
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    • Excess endogenous insulin has measurable C-peptide (not so with excess exogenous insulin)
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Hypoglycemia (5)

  • Standard treatment options
    • D50
    • D25 (peds)
    • D10 (neonates)
    • Glucagon 1 mg IM/IV (converts liver glycogen to glucose)
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    • D10 drip if recurrent or overdose
    • Hydrocortisone (adrenal insufficiency)
    • Octreotide – inhibits insulin secretion and helps prevent rebound hypoglycemia in the setting of glucose infusion treatment of refractory sulfonylurea-induced hypoglycemia
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Oral Agents In Diabetes Treatment (1)

  • Two classes: hypoglycemics & antihyperglycemics
  • Hypoglycemic agents:
    • Sulfonylurea agents
      • Chlorpropamide, tolbutamide, acetohexamide tolazamide, glipizide, glyburide, glimepiride
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      • Stimulate pancreatic insulin secretion
      • Cause profound hypoglycemia in overdose
      • Long duration of action
      • Chlorpropamide also can cause SIADH
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    • Repaglinide (Prandin)
      • Can also cause hypoglycemia
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Oral Agents In Diabetes Treatment (2)

  • Antihyperglycemic agents
  • Less likely to cause hypoglycemia in overdose
    • Metformin
      • Rarely causes lactic acidosis
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    • Alpha-glucosidase inhibitors
      • Inhibit intestinal hydrolysis of polysacharides
      • Oral sucrose will not be absorbed
    • Thiazolodenediones (Avandia/Actos)
      • Limited overdose experience
      • Can worsen CHF
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      • Other side effects
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Hypoglycemia Pearls

  • Always admit if sulfonylurea overdose
    • Most symptomatic in 4 hours (can be delayed)
    • Octreotide inhibits insulin secretion
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  • Give thiamine with glucose in hypoglycemic malnourished patients
  • Glucagon may not be effective in chronic alcoholics, those with liver disease or infants with low, liver glycogen stores
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Diabetic Ketoacidosis Pathophysiology

  • Relative lack of insulin + stressors causes hyperglycemia
  • Hyperglycemia-induced osmotic diuresis causes polyuria, dehydration, hypovolemia, electrolyte loss (K, Mg, Phos)
  • Switch over to fat breakdown for energy source causes ketonemia (acidosis)
  • Metabolic acidosis causes compensatory hyperventilation (Kussmaul respirations)
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Precipitants of DKA

  • The "I's" have it!
    • Infection (UTI, pneumonia, pancreatitis)
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    • Infarction (e.g. AMI)
    • Infraction (noncompliance)
    • IUP (pregnancy)
    • Ischemia (CVA)
    • Illegal (substance abuse)
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    • Iatrogenic (drug interactions)
    • Idiopathic (new onset DM)
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Fluids / Bicarbonate in DKA

  • Initial fluid resuscitation for hypovolemia
  • Replace electrolytes (phosphate, potassium)
  • Insulin drip (after checking potassium)
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  • Sodium bicarbonate is rarely indicated
    • The hazards of bicarbonate use include
      • Paradoxical CSF acidosis
      • Decreased oxygen-hemoglobin dissociation (shifts curve to left)
      • Overload of sodium
      • Hypokalemia, hypophosphatemia
      • Cerebral edema in children
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Sodium / Phosphate in DKA

  • Pseudohyponatremia
    • (*Hyperosmolar as opposed to hypoosmolar state)
    • Sodium is artifactually ? 1.6mEq/L for every 100 mg/dL ? glucose over 100

Hypophosphatemia is possible: Respiratory depression, muscle weakness CHF, decreased mental status (failure to generate adequate ATP)

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Potassium in DKA

  • Serum K+ level may be elevated, normal or low
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  • Initial hypokalemia indicates massive total body depletion (usual deficit is 3-7 mEq/L)
  • Replacement recommendations
    • K < 3.3: Hold insulin, give 40 mEq per hour until = 3.3
    • K = 3.3 but < 5.0: give 20-30 mEq in each liter IVF to keep K 4-5 mEq/L
    • K = 5.0: No replacement but check Q2 hr
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  • Serum potassium will decline with insulin and correction of acidosis (drives K+ into cells)
  • Cardiac arrest in DKA is often 2° to precipitous hypokalemia (insulin therapy, acidosis correction or fluid therapy with increased urinary losses)
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Complications of DKA Treatment

  • Hypoglycemia due to excess insulin
    • Add glucose administration when glucose = 250 mg/dl
  • Hypokalemia is associated with insulin administration, bicarbonate, hydration
  • Bicarbonate therapy causes CSF acidosis
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  • Cerebral edema
    • Patients at risk: Young, new onset DM
    • Controversial: Possibly 2° to over-hydration, rapid osmotic changes, hypoxemia, sodium bicarbonate
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Alcoholic Ketoacidosis (1)

  • Binge drinking with heavy alcohol consumption and decreased food intake for several days (starvation ketosis)
  • Imbalance of insulin levels and counter-regulatory hormones
  • Ethanol metabolism inhibits gluconeogenesis
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  • Abdominal pain, nausea, vomiting, dehydration, disorientation
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Alcoholic Ketoacidosis (2)

  • Alcohol levels are usually low or negative and glucose is often mildly elevated with low bicarbonate and high anion gap
  • Urinary ketones may be weakly positive
  • Treatment: Glucose + saline (D5NS), thiamine and potassium repletion

The major and earliest ketone produced from fat breakdown is beta-hydroxybutyrate, but the lab-measured ketone is acetoacetate. Therefore, lab tests for ketones may be falsely negative.

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Hyperosmolar Hyperglycemic Non-ketotic State HHNS (1)

  • Similar to DKA but has important distinctions
    • No ketoacidosis
    • Glucose is usually higher, often >1000
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    • Serum osmolality is often greater than 350
    • Most often occurs with NIDDM
    • Higher mortality than DKA
    • DKA has shorter onset
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  • Precipitating factors include
    • Infection, especially pneumonia
    • Myocardial infarction
    • CVA
    • GI bleed
    • Pyelonephritis
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    • Pancreatitis
    • Uremia
    • Subdural hematoma
    • Peripheral vascular occlusion
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Hyperosmolar Hyperglycemic Non-ketotic State HHNS (2)

  • Common comorbid conditions
    • Renal insufficiency
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    • Vascular disease
    • Poor access to water
  • Common associated medications
    • Diuretics
    • Propranolol
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    • Corticosteroids
    • Calcium channel blockers
    • Phenytoin
    • Cimetidine
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HHNS is often the initial presentation of NIDDM

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Hyperosmolar Hyperglycemic Non-ketotic State HHNS (3)

  • Physical findings
    • Dehydration
    • Altered sensorium
    • Focal neurologic findings (often mistaken for a stroke)
    • Coma is rare
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  • Treatment
    • Normal saline
    • Average fluid deficit 8-12 liters
    • ½ of deficit in first 12 hours, rest over next 24 hours
    • Initial 1-2 liter bolus as clinically indicated
    • Insulin infusion (usually lower doses than in DKA)
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Cerebral edema possibly 2° to rapid fluid replacement or the severity of the condition

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Thyroid Hormones

  • TRH from hypothalamus stimulates TSH release from anterior pituitary
  • TSH stimulates thyroid gland
    • Thyroid hormones (T3, [20%] T4 [80%]) are synthesized and released
    • Thyroid hormone production depends on iodine intake. Excess iodine blocks hormone release
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  • T3 is biologically 4x more active than T4
  • T3 and T4 provide feedback inhibition of TSH release
  • T3 and T4 act on cells
    • Increase rate of cell metabolism
    • Increase rate of protein synthesis
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Hyperthyroidism (1)

  • Causes
    • Graves' disease (most common):
      • An autoimmune disorder (thyroid-stimulating immunoglobulins mimic the action of TSH)
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    • Toxic thyroid adenoma, toxic multi-nodular goiter
    • Thyroiditis
    • Pituitary adenoma
    • Excess iodine in diet
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Goiter

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Hyperthyroidism (2)

  • Signs and symptoms
    • Nervousness, tremor, insomnia
    • Heat intolerance, sweating
    • Weakness, weight loss, hair loss
    • Tachycardia, palpitations
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    • Hyperdefecation
    • Irregular menses
    • Goiter / thyroid bruit
    • Exopthalmos (Grave's only), lid lag (the lids move more slowly than the eyes)
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Hyperthyroidism (3)

Pre-tibial Myxedema

  • Rare manifestation of Graves' disease
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  • Bilateral, elevated, firm dermal nodules and plaques
  • Skin yellow or waxy
  • Accumulation of mucopolysaccharides
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Hyperthyroidism (4)

  • Risk factors: female, family history, other autoimmune disease
  • Lab: Increased T3 and T4, decreased TSH
  • Treatment
    • Beta blockers
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    • PTU
    • Radioactive iodine
    • Surgery
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Thyroid Storm (1)

  • A life-threatening complication of hyperthyroidism. May not be directly related to magnitude of excess thyroid hormone
  • Precipitating events include
    • Withdrawal of antithyroid medications
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    • Administration of IV contrast
    • Thyroid hormone overdose
    • Pneumonia
    • CVA
    • Pulmonary embolus
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    • Toxemia of pregnancy
    • Diabetes
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Thyroid Storm (2)

Thyroid storm is a clinical diagnosis The hallmark is CNS dysfunction

  • Other diagnostic criteria include
    • Temperature > 38 °C
    • Tachycardia out of proportion to the fever
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    • Exaggerated peripheral manifestations of thyrotoxicosis, including tremor and weakness
  • No laboratory tests distinguish thyroid storm from simple hyperthyroidism – it is a clinical diagnosis
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Thyroid Storm (3)

  • Thyrotoxicosis / thyroid storm is associated with
    • Elevated free T4 level
    • Decreased TSH level
    • Hyperglycemia
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    • Hypercalcemia
    • Elevated LFTs
    • Low cholesterol
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Thyroid Storm Treatment

  • Five step ORDERED approach
    1. General supportive care: IV fluids, correct electrolyte imbalance, corticosteroids (decrease peripheral conversion of T4 to T3), no ASA (displaces thyroid hormone from thyroglobulin)
    2. Blockade of peripheral thyroid hormone effects: Propranolol 1 mg to 10 mg titrated to symptoms
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    4. Blockade of thyroid hormone synthesis: PTU (also inhibits peripheral conversion of T4 to T3)
    5. Blockade of thyroid hormone release: iodine given one hour after PTU
    6. Identification and treatment of precipitating events
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Apathetic Thyrotoxicosis

  • Rare disorder seen in elderly patients
  • Lethargy, slowed mentation, apathetic facies
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  • Goiter is usually present
  • Droopy eyelids are common
  • No exophthalmos, stare or lid lag
  • Symptoms of apathetic hyperthyroidism may be masked because of underlying organ dysfunction
  • Resting unexplained tachycardia
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  • Resistant atrial fibrillation and CHF are common
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Hypothyroidism (1)

  • Causes
    • Treatment of Graves' disease
    • Iodine deficiency in diet
    • Autoimmune destruction of thyroid gland (e.g. Hashimoto's)
    • Lithium therapy for bipolar disorder
    • Amiodarone
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    • Pituitary and hypothalamic disorders (rare)
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Hypothyroidism (2)

  • Signs and symptoms
    • Weakness, lethargy
    • Cold intolerance
    • Hypothermia
    • Weight gain
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    • Constipation
    • Dry, thick skin
    • Generalized nonpitting edema (myxedema)
    • Prolonged, heavy periods
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Hypothyroidism (3)

  • Clinical signs of severe hypothyroidism include
    • Dermatologic: coarse, waxy skin, loss of lateral third of eyebrows, scant pubic hair, puffy face and extremities (myxedema)
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    • CNS: slowed mentation, altered mental status, psychosis ("myxedema madness"), coma
    • Cardiac: CHF, bradycardia, hypotension, cardiomegaly, pericardial effusion, low voltage
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Hypothyroidism (4)

  • Lab
    • Low T4, elevated TSH (unless problem with hypothalamus or pituitary)
    • Elevated lipids
    • Hyponatremia (dilutional)
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    • Anemia
  • Myxedema coma
    • Hypoxemia
    • Hypothermia
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Myxedema Coma (1)

  • The end of the spectrum of hypothyroidism
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  • Life-threatening, rare, elderly females, winter
  • Precipitating factors include
    • Stressors: MI, infections, trauma, cold exposure
    • Drugs are metabolized slower and therefore have increased effects (narcotics, tranquilizers, beta blockers, amiodarone)
    • Non-compliance with thyroid replacement
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Myxedema Coma (2)

  • Signs
    • "Hung up" reflexes (prolonged relaxation phase of DTRs)
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    • Hypothermia
    • Non-pitting periorbital edema (puffy eyelids)
    • Generalized non-pitting edema
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Myxedema Coma (3)

  • Treatment
    • Supportive care: Rewarming, fluid support, search for underlying cause
    • Specific treatment
      • IV thyroxine (T4). May require large doses
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      • IV T3 is not recommended (can cause V-tach)
    • Corticosteroids (because of possible unrecognized adrenal or pituitary insufficiency)
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Adrenal Gland

  • Clinical manifestations primarily due to
    • Cortisol (affects metabolism of most tissues, glucose regulation, increases blood glucose)
    • Aldosterone (renal Na+ reabsorption & K+ excretion)
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Adrenal Insufficiency (1)

Primary Adrenal Failure

  • Idiopathic (autoimmune): Addison's Disease
  • Infiltrative, infectious
    • Sarcoid, amyloid
    • TB, fungal, septicemia
  • Hemorrhage, infarction
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  • Neoplastic
  • Drugs (etomidate)
  • Bilateral adrenal failure is associated with meningococcemia (Waterhouse-Friderichsen)
    • Presents with abdominal pain, vomiting, fever, hypotension
  • Diagnosis by serum cortisol level or corticotropin stimulation test
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Hyperpigmentation is seen in Addison's disease

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Adrenal Insufficiency (2)