Chapter 41

Chapter 41: Endocrine Problems Affecting Growth and Metabolism (Simplified)
How Endocrine Function Can Change

  • Not enough hormone (Hypofunction):

    • The gland makes too little hormone.

    • Why it happens:

      • Born with a defect.

      • Poor blood flow, infections, swelling, immune system attacking itself, or tumors.

      • Normal aging.

      • Gland shrinks due to medicines or unknown reasons.

      • Problem with hormone receptors on cells.

  • Too much hormone (Hyperfunction):

    • The gland makes too much hormone.

    • Why it happens:

      • Gland is overstimulated or grows too much (hyperplasia).

      • Tumor on the gland that produces hormones.

  • Hormone Resistance:

    • The body's cells don't respond well to the hormone.

    • Why it happens:

      • Cells inside don't react to hormone signals.

      • Receptors on the target cells are faulty.

Types of Endocrine Disorders: Where the Problem Starts

  • Primary Disorders:

    • The problem is directly in the gland that makes the hormone (e.g., thyroid problem).

  • Secondary Disorders:

    • The gland itself is okay, but it's not getting the right signals (stimulating hormones or releasing factors) from the pituitary gland.

  • Tertiary Disorders:

    • The problem is in the hypothalamus (the brain area that controls the pituitary). This means both the pituitary and the target gland don't get enough stimulation.

Pituitary Gland and Growth Issues

  • Pituitary Tumors:

    • Growths in the pituitary gland.

    • Types:

      • Original tumors (start in the pituitary).

      • Secondary tumors (cancer that spread from elsewhere).

      • Functional tumors (make pituitary hormones).

      • Nonfunctional tumors (don't make hormones).

  • Hypopituitarism (Low Pituitary Hormones):

    • The pituitary gland doesn't make enough hormones. This can be serious.

    • Signs:

      • Usually develop slowly but can be sudden and dangerous.

      • Ongoing tiredness.

      • Weakness and fatigue.

      • Poor appetite.

      • Sexual problems.

      • Can't stand the cold.

  • Growth Hormone (GH):

    • Made by the anterior pituitary gland.

    • Jobs of GH:

      • Helps bones grow longer in children.

      • Makes cells grow bigger and divide faster.

      • Helps cells absorb amino acids (for protein).

      • Makes cells use fats more for energy.

      • Makes cells use carbohydrates less for energy.

  • Growth Hormone Deficiency in Children:

    • Not enough GH stops bones from growing, leading to short height or dwarfism.

  • Growth Hormone Excess (Too Much GH):

    • Leads to too much bone growth, called gigantism (very tall).

Why Some Children Are Short

  • Normal variations.

  • Born small (low birth weight).

  • Long-term illness and poor nutrition.

  • Endocrine problems (hormone issues).

  • Chromosome problems.

  • Bone problems.

  • Rare conditions.

  • Genetic Short Stature:

    • Child is well-proportioned and height is similar to parents' height.

  • Constitutional Short Stature:

    • Child is moderately short, thin, has delayed bone and sexual development, and no other clear cause for slow growth.

  • Other Reasons for Short Stature:

    • Not enough protein or calories.

    • Chronic illnesses (e.g., severe kidney disease, uncontrolled diabetes).

    • Problems absorbing nutrients.

    • Taking too much steroid medicine (glucocorticoids).

    • Emotional stress.

Why Some Children Are Tall

  • Constitutional Tall Stature:

    • Child is taller than peers but growing at a normal rate for their bone age.

  • Genetically Tall:

    • Taller because of genes.

  • Other Reasons for Tall Stature:

    • Marfan syndrome (a connective tissue disorder).

    • Endocrine problems like early puberty (early start of sex hormone release, too much GH).

  • Hormone Excess in Adults (Acromegaly):

    • Too much GH after growth plates close.

    • Cartilage parts of the skeleton grow too much.

    • Heart and other organs get bigger.

    • Metabolism changes, affecting fat and sugar levels.

  • Causes of Acromegaly:

    • Most common (95%): A tumor in the pituitary gland that makes too much GH.

    • Less common (<5%): Other tumors making hormones that stimulate GH release.

  • Treatment Goals for Acromegaly:

    • Get GH levels back to normal after a sugar drink.

    • Get IGF-1 levels back to normal for age/sex.

    • Remove or shrink the tumor.

    • Relieve pressure symptoms from the tumor.

    • Improve physical signs.

    • Return mortality rate to normal.

Early Puberty (Precocious Puberty)

  • Definition:

    • Sexual development starts too early because the brain signals the sex glands too soon.

  • Effects:

    • Children with early puberty are usually tall during childhood but end up shorter as adults because their growth plates close early.

  • Causes of Early Sexual Development:

    • Unknown (idiopathic).

    • Problems with the ovaries/testes.

    • Problems with the adrenal glands.

    • Problems with the hypothalamus.

    • Brain tumors, both non-cancerous and cancerous.

Thyroid Gland Problems

  • Anatomy:

    • The thyroid is a butterfly-shaped gland located in the front of your neck, just below your voice box.

  • Main Jobs of Thyroid Hormone:

    • Increases body's metabolism (how fast cells work) and making proteins.

    • Important for normal growth and brain development in children (mental development, sexual maturity).

  • Thyroid Hormone Carriers:

    • Three main proteins carry thyroid hormones in the blood:

      • Thyroid hormone-binding globulin (TBG): Carries about 70% of T4 and T3.

      • Thyroxine-binding prealbumin (TBPA): Carries about 10% of T4 and less T3.

      • Albumin: Carries about 15% of T4 and T3.

  • Tests for Thyroid Problems:

    • Blood tests for T3, T4, and TSH levels.

    • Resin uptake test.

    • Checking for thyroid antibodies (immune system attacking thyroid).

    • Radioiodine (123I) uptake test (measures how well the thyroid absorbs iodine).

    • Thyroid scans (imaging using tracers).

    • Ultrasound.

    • CT and MRI scans.

    • Fine-needle aspiration (FNA) biopsy (taking a small sample from a lump in the thyroid).

  • Changes in Thyroid Function:

    • Hypothyroidism (Underactive Thyroid):

      • Slowed metabolism, fluid buildup in tissues (myxedema), high cholesterol.

      • Can cause a goiter (enlarged thyroid).

    • Hyperthyroidism (Overactive Thyroid):

      • Increased metabolism, more oxygen use, increased energy use, overactive sympathetic nervous system.

  • Signs of Hyperthyroidism:

    • Extreme restlessness, easily annoyed, anxious.

    • Can't sleep, increased heart output, fast heart rate (tachycardia), palpitations.

    • Diarrhea, increased hunger.

    • Shortness of breath, can't stand heat, increased sweating.

    • Thin and silky skin and hair, weight loss.

  • Signs of Thyroid Storm (Severe Hyperthyroidism):

    • Very high fever.

    • Severe heart problems (very fast heart rate, heart failure, chest pain).

    • Severe brain/nervous system effects (agitation, restlessness, confusion).

    • Very high risk of death.

  • Graves Disease:

    • A type of hyperthyroidism with an enlarged thyroid (goiter) and eye problems (ophthalmopathy), sometimes skin problems.

    • It's an autoimmune disease where the body's immune system wrongly stimulates the thyroid gland.

    • Runs in families.

  • Signs of Hypothyroidism:

    • Slow mental and physical activity, fluid buildup (myxedema), sleepiness.

    • Decreased heart output, slow heart rate (bradycardia), constipation.

    • Poor appetite, slow breathing, can't stand cold.

    • Coarse dry skin and hair, weight gain.

  • Congenital Hypothyroidism (Hypothyroidism at Birth):

    • Crucial for normal growth and brain development; long-term lack leads to mental disability and poor physical growth, known as cretinism.

Adrenal Gland Problems

  • Anatomy:

    • The adrenal glands are two small glands, one on top of each kidney.

  • Stages of Adrenal Cortical Insufficiency (Not Enough Adrenal Hormones):

    • Primary adrenal cortical insufficiency (Addison disease):

      • The adrenal gland itself is damaged, leading to low hormone levels and high ACTH (a stimulating hormone).

    • Secondary adrenal cortical insufficiency:

      • Caused by problems with the pituitary gland or its removal, not the adrenal gland itself.

    • Acute adrenal crisis:

      • A sudden, life-threatening drop in adrenal hormones.

  • Signs of Adrenal Insufficiency:

    • Loss of appetite, weight loss, exhaustion, weakness, stomach problems (nausea, diarrhea).

    • Muscle pain, joint pain, abdominal pain.

    • Low blood pressure when standing up (orthostatic hypotension), low sodium, high potassium, dark skin patches.

    • Other hormone deficiencies and related autoimmune diseases.

  • Hormones from the Adrenal Cortex:

    • Mineralocorticoids (e.g., aldosterone): Control salt, potassium, and water balance.

    • Glucocorticoids (e.g., cortisol): Manage metabolism, control inflammation; vital for surviving stress.

    • Adrenal Sex Hormones (androgens): A source of male hormones for women.

  • Jobs of Cortisol:

    • Helps with sugar, protein, and fat metabolism.

    • Acts against inflammation.

    • Affects mood and plays a role allowing other hormones to work.

  • Common Enzyme Deficiencies:

    • Congenital adrenal hyperplasia: Too much ACTH leads to too many adrenal male hormones and mineralocorticoids.

    • 21-Hydroxylase deficiency: Accounts for more than 90% of cases.

    • 11-β-Hydroxylase deficiency.

  • Addison Disease vs. Cushing Syndrome:

    • Addison Disease:

      • All layers of the adrenal cortex are destroyed, leading to low hormone production and high ACTH levels.

      • Causes dark skin spots; requires lifelong hormone replacement, with higher doses during stress.

    • Cushing Syndrome (Too Much Cortisol):

      • Types:

        • Pituitary form: Excess ACTH from a pituitary tumor.

        • Adrenal form: From non-cancerous or cancerous adrenal tumors.

        • Ectopic form: ACTH made by tumors elsewhere in the body.

      • Signs:

        • Changes in fat distribution (e.g., moon face, buffalo hump), muscle weakness and wasting, purple stretch marks, weak bones (osteoporosis), high blood sugar, low potassium, increased stomach acid, excess hair (hirsutism), irregular periods.

  • Difference:

    • Addison disease: Not enough adrenal hormones due to gland destruction.

    • Cushing syndrome: Signs of too much cortisol from any cause.

How the Body Controls Blood Sugar

  • Hormones Controlling Metabolism:

    • Glucose Metabolism: Controlled by blood sugar levels.

    • Fat Metabolism: Related to ketones (chemicals produced when fat is burned).

    • Protein Metabolism: Involves amino acids.

  • Hormones Regulating Blood Sugar:

    • Mainly from the pancreas:

      • Insulin: Helps cells absorb and store glucose (sugar). It also stops fat/glycogen breakdown and sugar production from other sources, increasing protein building.

      • Glucagon: Raises blood sugar.

    • Other hormones: somatostatin, amylin, and hormones from the gut.

  • Counterregulatory Hormones (Oppose Insulin):

    • These hormones work against insulin to keep blood sugar levels up during fasting, exercise, or when glucose is low.

    • Epinephrine (adrenaline).

    • Growth Hormone.

    • Glucocorticoid Hormones (like cortisol).

  • Other Energy-Controlling Hormones:

    • Insulin, glucagon, epinephrine, growth hormone, glucocorticoids.

Diabetes Mellitus and Metabolic Syndrome

  • Facts (2020):

    • 37.3 million people in the U.S. have diabetes; most have type 2.

    • More common in certain ethnic groups.

    • Type 1 diabetes is more common in children.

  • Tests for Diagnosis and Management:

    • Blood tests:

      • Fasting plasma glucose test (blood sugar after not eating).

      • Random glucose test.

      • Oral glucose tolerance test (measures sugar levels after a sugary drink).

      • Continuous glucose monitoring.

      • Hemoglobin A1C (average blood sugar over 2-3 months).

    • Urine tests.

  • Prediabetes:

    • Blood sugar levels are higher than normal but not high enough for a diabetes diagnosis.

  • Type 1 Diabetes Mellitus:

    • The body doesn't produce insulin.

  • Type 2 Diabetes Mellitus and the Metabolic Syndrome:

    • The body doesn't use insulin effectively.

  • Gestational Diabetes Mellitus:

    • Diabetes that develops during pregnancy.

  • Diabetes from Other Causes.

Diabetes Complications

  • Acute (Sudden, Short-Term) Complications:

    • Diabetic Ketoacidosis (DKA):

      • Rapid, deep breathing (Kussmaul respiration); high blood sugar, ketones in blood/urine, blood becomes too acidic.

    • Hyperosmolar Hyperglycemic State (HHS):

      • Very high blood sugar, severe dehydration, no ketones, altered mental state; common in type 2 diabetes.

    • Hypoglycemia (Low Blood Sugar):

      • Blood glucose below 70 mg/dL (with or without symptoms).

  • Complications Related to Hormones That Raise Blood Sugar:

    • Somogyi Effect:

      • Insulin causes low blood sugar at night, which then triggers the release of hormones that raise blood sugar, leading to high blood sugar in the morning.

    • Dawn Phenomenon:

      • Blood sugar rises in the early morning hours, not due to low blood sugar the night before.

  • Chronic (Long-Term) Complications:

    • Microvascular (Small Blood Vessel) Complications:

      • Nerve damage (neuropathy), eye damage (retinopathy), kidney disease (nephropathy), digestive problems.

    • Macrovascular (Large Blood Vessel) Complications:

      • Heart disease (coronary artery disease), stroke, poor circulation in legs/feet (peripheral vascular disease).

    • Diabetic Foot Ulcers.

    • Weakened Immune System:

      • Higher risk of infections and severe illness (like COVID-19).