Ch 79 Pt 1

Endocrine System Overview

The endocrine system is like the body's control center, using special chemical messengers called hormones. These hormones are made by glands and sent directly into the bloodstream to tell different parts of the body what to do. They help control many important body jobs, such as how your body uses water, balances salts, digests food, uses sugar for energy, sends nerve signals, handles stress, fights swelling, and controls reproduction. Even though glands might have different names, they all work together through their hormones to keep your body in a stable, healthy state (called homeostasis).

Major Glands and Hormones

  • Anterior pituitary: Makes hormones for growth (GH), thyroid control (TSH), adrenal gland stimulation (ACTH), milk production (prolactin), and reproductive organ control (FSH, LH).

  • Posterior pituitary: Makes hormones for controlling water in the body (ADH, also called vasopressin) and for labor and milk release (oxytocin).

  • Thyroid: Makes thyroid hormones (T4 and T3) that control your body's energy use, and calcitonin, which helps lower calcium in the blood.

  • Parathyroid: Makes parathyroid hormone (PTH), which helps raise calcium in the blood.

  • Adrenal cortex: Makes cortisol (for stress and metabolism), aldosterone (for salt and water balance), and sex hormones.

  • Adrenal medulla: Makes epinephrine (adrenaline) and norepinephrine, which prepare your body for "fight or flight" situations.

  • Pancreatic islets: Makes insulin (lowers blood sugar) and glucagon (raises blood sugar).

  • Gonads (sex glands): Make testosterone (in testes), and estrogens and progesterone (in ovaries), which control reproductive development and function.

  • Key functions:

    • GH: Helps body tissues grow.

    • TSH: Tells the thyroid to make its hormones.

    • ACTH: Tells the adrenal cortex to release cortisol.

    • Prolactin: Helps make breast milk.

    • FSH/LH: Important for reproductive organ maturity and how they work.

    • ADH: Makes kidneys save water.

    • Oxytocin: Causes contractions during labor and milk to be released.

    • T4/T3: Control how fast your body uses energy (metabolism).

    • Calcitonin: Lowers the amount of calcium in your blood.

    • PTH: Increases the amount of calcium in your blood.

    • Epinephrine/Norepinephrine: Start the body's emergency response.

    • Cortisol: Controls metabolism and the body's response to stress.

    • Aldosterone: Helps keep salt and water balanced.

    • Insulin: Lowers blood sugar; Glucagon: Raises blood sugar.

    • Testosterone/Estrogen/Progesterone: Control reproductive development and function.

Diagnostic Tests Overview

  • Pituitary function tests: Doctors use imaging (like X-rays or CT scans) and blood/urine tests to find out if there are problems with the pituitary gland.

  • Thyroid function tests (TFTs): Usually a group of tests (no single test tells everything); common ones check TSH, free T4, and T3 levels.

  • Thyroid imaging: Includes a thyroid scan (a special radioactive scan), radioactive iodine uptake (RAIU) test, and thyroid ultrasound.

  • Parathyroid tests: Check levels of parathormone (PTH), calcium, phosphate in blood, and calcium in urine; sometimes imaging is used.

  • Adrenal tests: Include the ACTH stimulation test, checking ACTH and cortisol in blood; also check for substances like VMA in urine (related to adrenaline-like hormones).

  • Pancreatic/endocrine diabetes tests: Used to check for diabetes.

    • Random blood glucose: Checks blood sugar at any time.

    • Fasting plasma glucose (FPG): Checks blood sugar after not eating for at least 8 hours; if it's 126 ext{ mg/dL} or more on two separate occasions, it suggests diabetes.

    • OGTT (oral glucose tolerance test): Used to confirm diabetes or check for gestational diabetes (diabetes during pregnancy); involves drinking a sugary drink and checking blood sugar levels.

    • HbA1c and estimated average glucose (eAG): Give an idea of average blood sugar over a few months.

  • Special thyroid tests:

    • RAIU uptake: Shows how much radioactive iodine the thyroid absorbs; normal is 15 ext{% to }45 ext{%}; in overactive thyroid, it can be up to about 90 ext{%}.

    • Thyroid ultrasound: Uses sound waves to look at lumps (nodules) and the thyroid's structure.

  • Other measurements:

    • HbA1c (glycated hemoglobin): Shows your average blood sugar over the last 2-3 months because it measures sugar attached to red blood cells.

    • eAG: Translates your HbA1c number into units you see on a regular blood sugar meter (e.g., if your HbA1c is 8%, your eAG is about 180 ext{ mg/dL}).

Pituitary Gland Disorders

  • Gigantism and Acromegaly: Too much growth hormone (GH).

    • In children, it causes gigantism (they grow unusually tall).

    • In adults, it causes acromegaly (bones in face, hands, and feet get bigger; lips thick, features coarse, organs enlarge).

    • Treatments: Can include radiation to the pituitary, surgery, or medicines like bromocriptine or somatostatin analogues.

  • SIADH (syndrome of inappropriate ADH): Too much ADH leads to the body holding onto too much water, making blood sodium levels drop (hyponatremia).

    • Management: Limit how much fluid a person drinks (usually 500 ext{ to }1000 ext{ mL/day}), use strong salt solutions in serious cases, or medicines like demeclocycline or lithium to lessen ADH effects.

  • Diabetes Insipidus: Not enough ADH or kidneys don't respond to it. Leads to making a lot of very watery urine (up to 15-20 liters in a day) and feeling very thirsty all the time (polydipsia).

    • Treatment: Medicine like desmopressin (DDAVP) or vasopressin.

  • Postoperative considerations (after surgery): Watch out for bleeding or difficulty breathing due to swelling. Make sure the breathing tube is ready if needed. After thyroid/pituitary surgery, sometimes the parathyroid glands are affected, leading to low calcium. Monitor calcium levels and look for signs of muscle spasms (tetany).

Thyroid Gland Disorders

  • Hyperthyroidism (e.g., Graves disease): The thyroid makes too much T4/T3, speeding up the body's metabolism.

    • Symptoms: Feeling too hot, losing weight even with a good appetite, fast heartbeat, bulging eyes, enlarged thyroid (goiter).

    • Treatments:

      • Antithyroid drugs (like PTU, methimazole) to stop the thyroid from making too many hormones.

      • Radioactive iodine (RAI) to destroy overactive thyroid tissue.

      • Thyroidectomy: Surgery to remove part or all of the thyroid for very large goiters or when other treatments don't work.

  • Hypothyroidism: The thyroid doesn't make enough thyroid hormone.

    • Congenital hypothyroidism (present from birth) can cause short stature and learning difficulties if not treated.

    • Adult hypothyroidism: Causes tiredness, weight gain, feeling cold, slow thinking.

    • Treatment: Taking thyroid hormone replacement medicine (levothyroxine, which is T4; sometimes liothyronine, which is T3).

    • Post-treatment caution: Be careful with sedatives for hypothyroid patients. Watch for signs of heart strain. It's important to slowly increase the medicine dose.

  • Goiter (simple): An enlarged thyroid gland, often caused by not enough iodine in the diet.

    • Treatment: Eating more iodine (iodized salt, iodine supplements). Surgery might be needed if the goiter is pressing on your throat or other structures.

  • Thyroid Neoplasms (lumps/growths):

    • Fluid-filled cysts may be drained.

    • Solid or cancerous lumps need surgery or radioactive treatment.

    • A biopsy (taking a small tissue sample) helps tell if a lump is harmless or cancerous.

  • Thyroidectomy post-op care (after thyroid removal surgery): Watch closely for bleeding, breathing problems, and muscle spasms (tetany) if parathyroid glands were accidentally damaged. Calcium levels might need checking and managing. If the whole thyroid is removed, hormone replacement medicine will be needed for life.

Parathyroid Gland Disorders

  • Hyperparathyroidism: Too much PTH, which causes high calcium in the blood (hypercalcemia) and bone weakening (osteoporosis spreading). Kidney stones can also form.

    • Management: Giving fluids and diuretics (water pills), and sometimes surgery to remove part of the parathyroid glands. Managing calcium levels before and after surgery is very important.

  • Hypoparathyroidism: Not enough PTH, leading to low calcium in the blood (hypocalcemia) and muscle spasms (tetany).

    • Signs: Positive Chvostek (twitching facial muscle when tapped) and Trousseau (hand spasm when blood pressure cuff is inflated) signs.

    • Treatment: Calcium supplements (calcium gluconate given into a vein if calcium is very low) and high doses of vitamin D. If the glands are removed, treatment is lifelong.

Adrenal Gland Disorders

  • Cushing syndrome (hyperadrenalism): Too much cortisol, either from a tumor or from taking too many steroid medicines.

    • Symptoms: Distinctive fat distribution (round or "moon" face, large stomach but thin arms/legs, a hump between shoulders), weak muscles, high blood pressure, trouble controlling blood sugar.

  • Addison disease (adrenal insufficiency): Not enough cortisol and aldosterone.

    • Symptoms: Dehydration, low sodium, high potassium, low blood pressure. Can be life-threatening if not treated.

  • Primary Aldosteronism: Too much aldosterone, causing high blood pressure and low potassium.

    • Treatment: Surgery to remove the affected adrenal gland may be an option.

  • Pheochromocytoma: A tumor in the adrenal medulla that makes too much adrenaline-like hormones.

    • Symptoms: Episodes of very high blood pressure, shaking, headache, fast heartbeat.

    • Diagnosis: Checked with a 24-hour urine test for VMA and imaging scans.

    • Treatment: Surgery to remove the tumor. If both adrenal glands are removed, lifelong steroid replacement medicine is needed.

Pancreatic Endocrine Disorders and Diabetes Mellitus

  • Diabetes Mellitus (DM): The body either doesn't make enough insulin or doesn't use it well, leading to high blood sugar.

    • Becoming more common due to rising obesity and inactive lifestyles.

    • Includes Type I (needs insulin shots), Type II (body resists insulin), gestational diabetes (GDM) (during pregnancy), and prediabetes (blood sugar higher than normal but not yet diabetes).

  • Prediabetes: Fasting blood sugar between 100 ext{ and }125 ext{ mg/dL}. High chance of developing full diabetes. Changing lifestyle can help prevent or delay it.

  • Type I DM (IDDM): The body's immune system attacks and destroys the cells in the pancreas that make insulin. Always needs insulin therapy.

  • Type II DM (NIDDM): The body's cells don't respond well to insulin, and the pancreas can't make enough to overcome this resistance. Managed with diet/exercise, pills, and sometimes insulin.

  • Gestational Diabetes Mellitus (GDM): Happens only during pregnancy. It increases the mother's risk of getting Type II DM later. Managed with diet, careful monitoring, and sometimes insulin.

  • Signs and symptoms (common across types of DM):

    • Polyuria: Urinating a lot.

    • Polydipsia: Feeling very thirsty.

    • Polyphagia: Feeling very hungry.

    • Weight changes.

    • Tiredness.

    • Blurred vision.

    • Frequent infections.

  • Metabolic syndrome: A group of conditions that include a large waistline, high blood pressure, high blood sugar, and unhealthy cholesterol levels. Greatly increases the risk of diabetes and heart disease.

  • Key glucose metrics:

    • Random glucose: Checks blood sugar at any time to screen for problems. High or low values need more testing.

    • Fasting Plasma Glucose (FPG): Normal is roughly 65 ext{ to }115 ext{ mg/dL}. Diabetes is diagnosed if it's ext{equal to or greater than } 126 ext{ mg/dL} on two occasions.

    • Oral Glucose Tolerance Test (OGTT): Used to confirm diabetes or for gestational diabetes screening. You drink a sugary drink, and your blood sugar is checked at specific times (usually 2 hours later).

    • HbA1c and Estimated Average Glucose (eAG): HbA1c shows average blood sugar over about 3 months. eAG converts HbA1c into the same units as regular glucose meters (e.g., an HbA1c of 8% means eAG is about 180 ext{ mg/dL}).

  • Urine testing in DM: Ketones in urine are checked in Type 1 DM, especially when blood sugar is high (over about 240 ext{ mg/dL}), to see if ketoacidosis (a serious condition) is developing. Ketones mean the body is burning fat for energy instead of sugar, which needs medical help.

  • Other DM considerations: Diabetes can lead to problems with large (macrovascular) and small (microvascular) blood vessels. Patients need to learn how to manage their condition, have regular check-ups, and take their medicines as prescribed.

Nursing and Care Considerations (condensed)

  • Work together: Plan and work with the healthcare team. Prepare patients for tests and care after surgery.

  • Monitor: Watch for signs of endocrine problems. Report abnormal lab results quickly.

  • Educate: Teach patients about lifelong hormone replacement (if needed), the importance of follow-up visits, taking medicines correctly, and recognizing signs of too much or too little hormone.

  • Emergencies: In serious situations like thyroid storm, myxedema coma, DKA (diabetic ketoacidosis), or adrenal crisis, start emergency care right away and make sure the patient is safe.