Endocrinology Quiz: Pituitary Function

Altered Functions of the Pituitary Gland

• The pituitary gland, the "master gland," is a small endocrine organ at the base of the brain.
• It has two parts:
  • Anterior pituitary (adenohypophysis): Produces and releases growth hormone (GH), prolactin (PRL), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH).
  • Posterior pituitary (neurohypophysis): Stores and releases oxytocin and vasopressin (ADH), produced in the hypothalamus.
• Pituitary disorders cause hormone imbalances:
  • Hypopituitarism (underactivity): Insufficient hormone production, often due to tumors, trauma, radiation, infections, or autoimmune conditions.
    • Symptoms include fatigue, weight loss, cold intolerance, low blood pressure, decreased appetite, infertility. In children, growth retardation is notable.
    • Associated disorders include adrenal insufficiency, hypothyroidism, hypogonadism, and growth hormone deficiency.
    • Treatment is hormone replacement therapy.
  • Hyperpituitarism (overactivity): Excessive hormone production, often due to pituitary adenoma (tumor).
    • Examples include acromegaly/gigantism (excess GH), Cushing's disease (excess ACTH), and prolactinoma (excess prolactin).
    • Symptoms vary depending on the affected hormone.
    • Treatment includes tumor removal, medication, or radiation therapy.
• Other pituitary-related conditions include diabetes insipidus (deficiency in ADH) and syndrome of inappropriate antidiuretic hormone (SIADH).

Altered Functions of the Thyroid Gland

• The thyroid gland is a butterfly-shaped gland in the neck, regulating metabolism and blood calcium.
• Key hormones:
  • Thyroxine (T4): A precursor converted to active T3.
  • Triiodothyronine (T3): The active hormone regulating metabolism.
  • Calcitonin: Regulates blood calcium levels.
• Thyroid function is regulated by the hypothalamus-pituitary-thyroid axis.
• Hypothyroidism (underactive thyroid): Insufficient hormone production, often caused by Hashimoto's thyroiditis, iodine deficiency, or thyroidectomy.
  • Symptoms include fatigue, weight gain, cold intolerance, dry skin, hair loss, constipation, and bradycardia.
  • Types include primary (direct thyroid dysfunction), secondary (pituitary failure), subclinical (mild), and myxedema (severe).
  • Diagnosis involves blood tests (elevated TSH, low T3/T4).
  • Treatment: Levothyroxine (synthetic T4).
• Hyperthyroidism (overactive thyroid): Excessive hormone production, often due to Graves' disease, toxic multinodular goiter, or thyroid adenoma.
  • Symptoms include weight loss, heat intolerance, increased appetite, tachycardia, anxiety, tremors, and excessive sweating. In Graves' disease, exophthalmos (bulging eyes) is more prevalent.
  • Types include Graves' disease, toxic nodular goiter, and thyroid storm.
  • Diagnosis involves blood tests (low TSH, high T3/T4) and imaging.
  • Treatment options are antithyroid medications, radioactive iodine therapy, or surgery.

Altered Functions of the Parathyroid Glands

• The parathyroid glands (4) regulate blood calcium, phosphate, and magnesium levels, primarily through parathyroid hormone (PTH).
• PTH functions: Increasing blood calcium by: stimulating osteoclasts (bone calcium release), enhancing kidney calcium reabsorption, and promoting vitamin D activation for calcium absorption, while reducing phosphate kidney reabsorption.
• Hyperparathyroidism (excess PTH):
  • Types: Primary (intrinsic gland issues, often adenomas), secondary (compensatory response to other conditions), and tertiary (autonomous PTH secretion).
  • Symptoms include bone pain, fractures, kidney stones, muscle weakness, gastrointestinal issues (nausea, constipation), and psychological symptoms (depression, confusion).
  • Diagnosis includes blood tests (elevated calcium and PTH) and imaging (ultrasound, sestamibi scan).
  • Treatment involves surgery (parathyroidectomy), medication (cinacalcet), and lifestyle adjustments.
• Hypoparathyroidism (deficient PTH):
  • Causes: Surgery, autoimmune destruction, genetics, or radiation.
  • Symptoms include neuromuscular signs (tetany, Chvostek's and Trousseau's signs), tingling/numbness, seizures, and cardiac arrhythmias.
  • Diagnosis involves blood tests (low calcium and PTH).
  • Treatment includes calcium and vitamin D supplements.

Altered Functions of the Adrenal Glands

• The adrenal glands sit atop the kidneys, regulating stress responses and electrolyte balance.
• Structure: Two parts: Adrenal cortex (produces corticosteroids) and adrenal medulla (produces catecholamines).
• Adrenal insufficiency (hypofunction): insufficient hormone production, includes Primary (Addison's disease; damage to adrenal cortex) and secondary (reduced ACTH from pituitary).
  • Symptoms include fatigue, weakness, low blood pressure, dehydration, altered pigmentation, nausea, vomiting, and electrolyte imbalances.
  • Diagnosis includes ACTH stimulation test and blood tests.
  • Treatment includes glucocorticoid and mineralocorticoids replacement therapy.
• Cushing's syndrome (hyperfunction): prolonged exposure to high cortisol levels, often from ACTH overproduction or adrenal tumors.
  • Symptoms include central obesity, hypertension, hyperglycemia, muscle weakness, thin skin (easy bruising), osteoporosis, infection susceptibility, mood changes.
  • Diagnosis includes dexamethasone suppression test and blood tests.
  • Treatment involves tumor removal, medication, and/or corticosteroid tapering.
• Pheochromocytoma: an adrenal medulla tumor releasing excessive catecholamines, causing paroxysmal hypertension, tachycardia, sweating, headaches, and anxiety.
  • Diagnosis includes blood and urine tests and imaging.
  • Treatment includes tumor removal and pre-operative blood pressure management.

Endocrine Disorders in Female and Male Reproductive Functions

• Female Reproductive Hormonal Disorders:
  • Primary ovarian insufficiency (POI): Premature ovarian failure (before age 40), causing low estrogen and irregular periods.
    • Causes include genetic factors, toxins, autoimmune issues, and idiopathic.
    • Symptoms include irregular periods, infertility, hot flashes, and vaginal dryness.
    • Treatment includes hormone replacement therapy, lifestyle changes, and psychological support.
  • Polycystic ovary syndrome (PCOS): Hormonal imbalance with multiple cysts, high androgens, and irregular periods.
    • Symptoms include irregular periods, excess hair growth (hirsutism), acne, and weight gain.
    • Can lead to diabetes and cardiovascular issues.
    • Treatment includes lifestyle changes, hormonal contraceptives, metformin, and anti-androgens.
  • Menopause: Natural cessation of ovarian function (around age 50), reducing hormone production.
    • Symptoms include hot flashes, vaginal dryness, sleep problems, and mood swings.
    • Complications include osteoporosis and cardiovascular issues.
    • Treatment involves hormone replacement therapy, lifestyle changes, and calcium/vitamin D supplementation.
• Male Reproductive Hormonal Disorders:
  • Hypogonadism: Insufficient testosterone production (primary: testicular failure; secondary: hypothalamic/pituitary dysfunction).
    • Symptoms include delayed puberty, reduced libido, erectile dysfunction, and infertility.
    • Treatment includes testosterone replacement therapy and fertility treatments.
  • Androgen insensitivity syndrome (AIS): Genetic inability to respond to androgens (testosterone).
    • Causes varying degrees of sexual ambiguity and female presentation when XY.
    • Treatment involves hormone therapy and possible surgeries.
  • Klinefelter syndrome: Extra X chromosome in males, leading to hypogonadism.
    • Symptoms include tall stature, reduced muscle mass, gynecomastia (breast development), and infertility.
    • Treatment includes testosterone replacement.
  • Hyperprolactinemia: High prolactin levels affecting testosterone and spermatogenesis (often due to pituitary tumors).
    • Symptoms include reduced libido, erectile dysfunction, infertility, and gynecomastia.
    • Treatment includes dopamine agonists and potentially surgery.

Cognitive and Neurological Disorders

• Cognitive disorders affect memory, learning, reasoning, and perception.

• Mild Cognitive Impairment (MCI): Subtle cognitive decline, more than normal aging, but not severe enough for dementia diagnosis.

  • Often forgetful, difficulties with complex tasks, mild daily life interference.

• Delirium: Acute confusion, disorientation, fluctuating attention, often from underlying medical conditions.

• Pseudodementia: Cognitive impairment mimicking dementia from psychiatric conditions (often depression).

• Dementia: Progressive cognitive decline without cure.

  • Reversible dementias:
    • Normal Pressure Hydrocephalus (NPH): Enlarged ventricles, urinary incontinence, gait disturbance, and cognitive decline. Treatment is VP shunt.
    • Vitamin B12 deficiency: Memory loss, numbness, and mood changes, blood levels are low to diagnose. Treatment is B12 supplementation.
  • Irreversible dementias:
    • Alzheimer's Disease: Gradual memory loss, language problems, and impaired executive function. Pathological signs are brain atrophy, amyloid plaques, and neurofibrillary tangles. Treatment involves cholinesterase inhibitors and NMDA receptor antagonists.
    • Vascular Dementia: Stepwise cognitive decline, often from small strokes. Treatment is underlying vascular risk factor management.
    • Lewy Body Dementia: Fluctuating cognition, visual hallucinations, and Parkinsonism. Treatments include cholinesterase inhibitors and limiting antipsychotic use.
    • Frontotemporal Dementia: Personality changes, impaired judgment, disinhibition in frontal and temporal lobe atrophy cases (often Pick's disease). Treatment is symptomatic, often with antidepressants/antipsychotics.
    • Parkinson's Disease Dementia: Parkinsonian motor problems with gradual cognitive decline. Treatment is Parkinsonian symptom management.
    • Huntington's Disease: Progressive genetic disorder causing chorea (involuntary movements) and cognitive decline. Treatment is symptomatic (tetrabenazine).
    • Wernicke-Korsakoff Syndrome: Thiamine deficiency from alcohol abuse, causes severe memory problems, confabulation (false memories), and ataxia (loss of coordination). Treat with Thiamine and cessation of alcohol.

• Stroke and Cerebral Ischemia: Interruption of blood flow to the brain causing neuronal death.

  • Types: Ischemic (clot/narrowing), hemorrhagic (bleeding).
  • Ischemic stroke treatment includes thrombolytic therapy (e.g., tPA) within timeframe. Hemorrhagic stroke treatment focuses on blood pressure control and potential surgery.

Fluid and Electrolyte Imbalances

• Fluid and electrolyte balance is crucial for cellular and metabolic function.
• Body fluid compartments: Intracellular fluid (60%), extracellular fluid (plasma, interstitial, transcellular).
• Key electrolytes: Sodium (Na+), Potassium (K+), Calcium (Ca2+), Magnesium (Mg2+), Phosphate (PO43-).
• Dehydration: Excessive fluid loss; caused by vomiting, diarrhea, sweating; symptoms include dry skin/mucous membranes, reduced urine output, hypotension, and confusion.
• Fluid overload (hypervolemia): Excessive fluid retention in the body. Caused by heart failure, kidney failure, excessive sodium. Symptoms include edema, hypertension, and pulmonary congestion.
• Electrolyte imbalances:
  • Hyponatremia (low sodium): Often from SIADH. Symptoms include nausea, confusion, and seizures.
  • Hypernatremia (high sodium): Often from dehydration or diabetes insipidus. Symptoms include thirst, agitation, and seizures/coma.
  • Hypokalemia (low potassium): Due to diuretics or GI issues. Symptoms include weakness and arrhythmias.
  • Hyperkalemia (high potassium): From kidney failure, acidosis, or tissue damage. Symptoms are muscle weakness and/or cardiac arrest.
  • Hypocalcemia (low calcium):
  • Hypercalcemia (high calcium):
• Fluid regulation: Homeostasis involves ADH, aldosterone, natriuretic peptides, osmosis/diffusion, and active transport.

Immune System Disorders

• The immune system protects the body from pathogens, abnormal cells, and foreign substances. Innate (nonspecific) immunity is a first-line defense. Adaptive (specific) immunity involves B and T lymphocytes.
• Primary immunodeficiencies: Congenital, from genetic defects, leading to defective immune components. Examples include SCID (both B and T cell defects), Bruton's agammaglobulinemia (B cell deficiency), DiGeorge syndrome (T cell deficiency), and Hyper-IgM syndrome (immunoglobulin class switching problems).
• Secondary immunodeficiencies: Acquired due to conditions like HIV/AIDS, cancer, chemotherapy, or malnutrition.
• Autoimmune diseases: Mistaken immune response to the body's own tissues. Examples include SLE (multisystem autoimmune attack), RA (joint inflammation), Hashimoto's (thyroid), and type 1 diabetes (pancreatic beta cell destruction).
• Hypersensitivity reactions: Overactive immune response. Types are categorized (Type I – immediate, Type II – cytotoxicity, Type III – immune complexes, Type IV – delayed).

Congenital Abnormalities and Teratogenic Disorders

• Congenital abnormalities are structural or functional defects present at birth.
• Teratogens cause congenital abnormalities, disrupting fetal development. Factors like timing of exposure and dose are key to severity.
• Examples:
  • Drugs (alcohol, androgens, phenytoin, excess vitamin A).
  • Infections (rubella, toxoplasmosis, varicella).
  • Physical agents (hyperthermia, radiation).
  • Maternal factors (diabetes, PKU).
• Congenital Anomalies:
  • External: Neural tube defects (spina bifida, anencephaly), orofacial clefts (cleft lip/palate), limb deficiencies (clubfoot).
  • Internal: Congenital heart defects (tetralogy of Fallot, transposition), gastrointestinal anomalies (esophageal atresia), genitourinary anomalies (renal agenesis).
  • Chromosomal disorders: Trisomy 21 (Down syndrome), Turner syndrome, Klinefelter syndrome.
• Abnormalities of metal metabolism:
  • Hemochromatosis (iron overload)
  • Wilson's disease (copper accumulation)
  • Menkes disease (copper deficiency).
• Management and prevention: Prenatal screening (ultrasound, blood tests), folic acid supplementation, teratogen avoidance, and maternal condition management. Treatment involves surgical correction and supportive care.

Altered Functions of the Pancreas

• The pancreas has exocrine (digestive enzymes) and endocrine (blood sugar regulation) functions.
• Pancreatic hormones: Insulin (lowers blood glucose), glucagon (raises blood glucose), somatostatin (inhibits insulin/glucagon), and pancreatic polypeptide.
• Diabetes mellitus (DM): Chronic hyperglycemia.
  • Type 1 DM: Autoimmune destruction of beta cells; requires lifelong insulin therapy.
  • Type 2 DM: Insulin resistance and inadequate insulin secretion; often linked to lifestyle factors; lifestyle modifications and oral hypoglycemics are common initial approaches. Gestational diabetes occurs during pregnancy.
• Acute pancreatitis: Sudden inflammation. Common causes are gallstones and alcohol abuse; severe abdominal pain radiating to the back and nausea/vomiting are notable symptoms.
• Chronic pancreatitis: Progressive damage, often from chronic alcohol abuse; persistent abdominal pain, steatorrhea (fatty stools), and significant weight loss are typical characteristics.
• Cystic fibrosis (CF): A genetic disorder impacting exocrine glands; causing thick mucus buildup. CF can lead to pancreatic insufficiency, recurrent lung infections, and growth problems.
• Pancreatic tumors: Benign or malignant; adenocarcinomas (most common pancreatic cancer) have symptoms like jaundice, weight loss, and abdominal pain. Insulinoma (a benign tumor of beta cells) causes hypoglycemia.

Renal Disorders

• The renal system filters blood, regulates fluids, controls blood pressure, and produces hormones.
• Acute Kidney Injury (AKI): Sudden kidney dysfunction; causes (prerenal - decreased blood flow, intrinsic - direct kidney damage, postrenal - urinary outflow obstruction); symptoms include oliguria, fluid retention, elevated BUN/creatinine. Treatment focuses on underlying causes.
• Chronic Kidney Disease (CKD): Gradual kidney function loss; common causes include diabetes and hypertension. Treatment focuses on managing underlying conditions and managing symptoms.
• Urinary Tract Infections (UTIs): Infections of urinary tract, commonly caused by Escherichia coli. Symptoms and treatment depend on localization (cystitis vs. pyelonephritis).
• Kidney Stones (Nephrolithiasis): Crystalline masses formed in urinary tract. Most stones are calcium oxalate. Symptoms include severe flank pain, hematuria. Treatment varies depending on stone size and location.
• Polycystic Kidney Disease (PKD): Genetic disorder causing fluid-filled cysts within kidneys; symptoms include hypertension, hematuria, flank pain, and potential kidney enlargement; diagnosis often involves ultrasound and genetic testing.