Thyroid and Parathyroid Disorders Lecture Notes PDF

Thyroid and Parathyroid Disorders Thyroid and Parathyroid Disorders Basic Concepts Endocrine glands: Chemical messengers (hormones) into blood Hypothalamus: Sends signals to the pituitary gland Anterior pituitary: Receives hormonal signals from hypothalamus Send out further signal...

Thyroid and Parathyroid Disorders Thyroid and Parathyroid Disorders Basic Concepts Endocrine glands: Chemical messengers (hormones) into blood Hypothalamus: Sends signals to the pituitary gland Anterior pituitary: Receives hormonal signals from hypothalamus Send out further signals Posterior pituitary: Releases hormones synthesized by hypothalamus End organs: Targets for pituitary hormones, may or may not secrete additional hormones Endocrine Disorders: Assessment and Diagnosis Current and past medical history Some disorders: Wide-ranging, multi-system signs May affect mood and behavior Immunoassays or blood levels of hormones Urinary hormone levels some instances Urine collection over 24 hours Suppression/stimulation tests CT scan/MRI; ultrasound  Hormone replacement therapy Dosage schedules attempt to mimic physiological effects Glucocorticoids, thyroid Endocrine hormones, sex steroids, ADH Disorders: most common replacements Treatments Suppression of hormone overproduction Medications, surgery, radiation Thyroid Triiodothyronine Thyroid disorder (T3) and thyroxine more common in Enlarged thyroid (T4) women Iodine required Primary thyroid Can indicate for synthesis disorders most hypo- or Thyroxine common hyperfunction Regulate body metabolism  Enlargement of the thyroid May or may not present with Goiter thyroid dysfunction signs and symptoms May develop with: Goitrogens Foods or other substances that Excess TSH Low iodine levels promote thyroid gland enlargement  Hashimoto’s thyroiditis Autoimmune disorder Anti-thyroglobulin and anti-thyroperoxidase antibodies Hypothyroidism Other causes Drugs Genetics Thyroiditis (postpartum period especially high incidence) Congenital hypothyroidism: Cretinism Hypothyroidism: Signs and Symptoms Cold intolerance Muscle cramps Weight gain Constipation Lethargy Decreased fertility Fatigue Puffy face Memory deficits Hair loss Poor attention span Brittle nails Hypothyroidism: Systemic Effects Factor Effect Reduced LDL receptors Hyperlipidemia Elevated carotene Yellow-orange skin Decreased hematopoiesis Anemia Decreased renal function Increased susceptibility to drug toxicity Myxedema Severe hypothyroidism Thyroid Disorders: Screening American Thyroid Women at age 35 and every 5 years thereafter Association American Women aged 50 and older who have one or more clinical College of features of the disorder Physicians Neonatal At birth, assess for elevated levels of TSH screening Identifies 90% of cases of congenital hypothyroidism Hypothyroidism: Diagnosis and Treatment Diagnosis Treatment Primary Replacement hormone High TSH, low free T3, low free T4 Levothyroxine Secondary Surgical intervention Low TSH, low free T3 and T4 Hashimoto’s thyroiditis Myxedema coma Antithyroglobulin (anti-Tg) Severe hypothyroid condition Antithyroperoxidase (anti-TPO) Will progress to confusion and coma if untreated Ultrasound Blood laboratory values Screening tests Hyperthyroidism Elevated free T3 and free T4 Graves’ disease Most common cause Thyroid-stimulating antibodies Autoimmune stimulation of the thyroid gland Specific HLA tissue types Thyroid-stimulating immunoglobulins (TSIs) TSH receptor antibody (TRAb) Anti-TPO and Anti-Tg antibodies Other causes Subacute thyroiditis Postpartum period thyroiditis Thyroid adenoma Excessive TSH Toxic multinodular goiter Hyperthyroidism Excessive iodine ingestion Jod-Basedow syndrome Secondary to pregnancy, HCG is similar to TSH  Nervousness Insomnia Sensitivity to heat Weight loss Hyperthyroidism: Enlarged thyroid gland Signs and Symptoms Atrial fibrillation Increased HR Increased sympathetic nervous system sensitivity Hyperthyroidism: Signs and Symptoms (continued_2) Exophthalmos Wide-eyed stare Extraocular area filled with mucopolysaccharides Graves ophthalmopathy Periorbital edema and bulging of the eyes Hyperthyroidism: Diagnosis and Treatment Diagnosis Treatment Graves’ Disease Antithyroid hormone medication Serum thyrotropin receptor Propylthiouracil (PTU), antibodies (TRAbs) Carbimazole Radioactive iodine uptake Radioactive I-131 ablation (RAIU) test Hot, warm, and cold nodules Ultrasound with color Doppler Surgical intervention evaluation Blood: TRH, TSH, T3, T4 levels Note: Biotin supplements can interfere with thyroid test accuracy Hypothyroidism vs. Hyperthyroidism Thyrotoxic Crisis (Thyroid Storm) Overwhelming release of thyroid hormones Serum-free T4 total T3: Highly elevated TSH level: Usually undetectable Stimulate metabolism High fever, tachycardia, agitation, psychosis Often precipitated by surgery or trauma Medical emergency Thyrotoxic Crisis (Thyroid Storm) Management Decrease thyroid hormone synthesis Methimazole or PTU Inhibit thyroid hormone secretion Oral potassium iodide or intravenous sodium iodide Reduce the heart rate Beta blocker and/or a calcium-channel blocker Support the circulation with stress doses of intravenous glucocorticoids  Thyroid Nodules Most asymptomatic Hypothyroidism or hyperthyroidism Single nodule: Increased malignancy risk Multiple nodules: Often benign Ultrasound and needle biopsy for diagnosis Technetium scan Uses radioactive isotope Hot, warm, cold nodule  Age younger than 20 years or older than 70 years Male sex Malignant History of neck irradiation Thyroid Nodule Firm, hard, or immobile nodule Presence of cervical lymphadenopathy  Four pea-sized glands on posterior thyroid Secrete PTH (parathyroid hormone) Parathyroid Gland Released: Blood calcium low Activates: Bone resorption Intestinal calcium absorption by kidneys Hypoparathyroidism and Hyperparathyroidism Hypoparathyroidism Hyperparathyroidism Rare Parathyroid adenoma Inadvertent damage: Thyroid surgery Primary: Elevated PTH and calcium Signs/symptoms of hypocalcemia Secondary: Response to hypocalcemia Chronic form: Diagnosis: Higher than normal BMD Blood tests for PTH and serum calcium But still may develop fractures Treatment: Replacement PTH Treatment: Recombinant human PTH 1–84 Parathyroidectomy for primary form Teriparatide (PTH 1–34) Treatment: Address hypocalcemia Treatment: Calcium and Vitamin D Reduce elevated serum calcium supplementation Alert! Myxedema coma May develop if hypothyroidism untreated Thyrotoxic crisis Medical emergency Heart failure and pulmonary edema in which of the following ways deos the thyroid gland use iodine? a. to produce the thyroid hormones- Thyroid replacement therapy is indicated for the treatment of ? a. myxedema