Endocrine BlueprintPANCE Blueprint

Diseases of Thyroid

• Hyperparathyroidism-

• Should be suspected when high serum calcium levels are detected

• Primary hyperthyroidism occurs due to PTH activation of osteoclasts leading to more bone reabsorption causing elevated calcium levels

• This also causes increased intestinal absorption of calcium

• Most common cause of primary hyperthyroidism is due to parathyroid adenoma

Hyperparathyroidism

• Diagnosis of primary hyperparathyroidism is made with a high PTH or one that is in the normal range but elevated inappropriately given the elevated given the patients hypercalcemia

• Patients with primary hyperparathyroidism are usually asymptomatic

• Elevated isolated serum calcium level should be repeated.

• Malignancy is another cause for hypercalcemia.  Malignancy and Primary Hyperparathyroidism account 90 percent of cases of hypercalcemia

Hyperparathyroidism

• If malignancy is present, the PTH level is usually normal or low, where as in primary hyperparathyroidism the levels are usually high

• Familial hypocalciuric hypercalcium (FHH) is due to an inactivating mutation of the calcium sensing receptor in the kidneys.  See a hypercalcemia with a mildly elevated PTH concentration

• Family history of hypercalcemia that is symptomatic is helpful for coming up with the diagnosis

• Thiazide diuretics reduce calcium urine excretion and can cause mild hypercalcemia

• Lithium decreases parathyroid gland sensitivity to calcium, and decreases urinary excretion.

Hyperparathyroidism• Secondary

Hyperparathyroidism is when the parathyroid appropriately responds to a reduced level of calcium.  This causes elevated PTH, the calcium absorption from the intestines to increase and increase bone reabsorption.

• Secondary Hyperparathyroidism has an elevated PTH and a low or normal calcium

• Secondary hyperparathyroid may come from renal failure and impaired calcitrol production and inadequate calcium uptake.  Vitamin D Deficiency can cause.

Hyperparathyroidism• Normocalcemic Primary

Hyperparathyroidism-secondary hyperparathyroid causes need to be ruled out.  Normal calcium and elevated PTH.  Vitamin D deficiency can cause

• Clinically most the time hyperparathyroidism can be asymptomatic

• Classic symptoms if present "bones, stones, abdominal moans, and psychic groans." Anorexia, nausea, constipation, polydipsia, bone pain, kidney stone, muscle weakness, polyuria, and psychiatric psychosis.

Hypoparathyroidism

• Most common cause is neck surgery on the thyroid or parathyroid

• After surgery hypoparathyroidism may be transient or may be permanent

• Clinically will see a low PTH and low serum calcium

• Calcium and vitamin D supplementation are the mainstays of hypoparathyroidism treatment

• Symptoms of hypoparathyroidism include:   tingling in hands and feet, involuntary muscle movements, muscle cramps, fatigue, irritability, anxiety, and depression

• Long term hypoparathyroidism can cause cataracts, dry skin, coarse hair, and brittle fingernails

Hyperthyroidism• Many disorders can cause

hyperthyroidism:  Graves Disease, Hashiomotos Thyrotoxicosis, Toxic Adenoma, Toxic Multiple Nodular Goiter, Iodine Induced Hyperthyroidism, Trophoblastic Disease from Germ Cell Tumors, TSH mediated hyperthyroidism, Thyroiditis, and exogenous and ectopic hyperthyroidism

• Graves Disease is the most common cause of hyperthyroidism.

• Graves Disease is an autoimmune disorder that causes thyrotropin (TSH) receptor antibodies, which stimulate thyroid gland growth and thyroid hormone synthesis and release.

Hyperthyroidism• Hashimoto's Thyroiditis is an autoimmune disease that causes patients

initially to present with hyperparathyroidism and high radio iodine uptake similar to Graves disease but eventually go hypothyroid

• Hypothyroid develops because of the infiltration of the thyroid gland with lymphocytes

• Toxic adenoma and multinodular goiter result from focal or diffuse hyperplasia of the thyroid follicular cells whose functional capacity is independent regulation of TSH.

• Toxic multinodular goiter tends to be more common in areas where iodine uptake is low

• Thyroid adenomas are not related to iodine uptake

• Iodine Induced Hyperthyroidism can occur after an iodine load such as IV contrast for CT scan, or amiodarone administration.

Hyperthyroidism• Iodine Induced Hyperthyroidism is rare

• Trophoblastic or germ cell tumors can be rare causes of hyperthyroidism

• Can occur as a hydatidiform mole in women

• Can occur in Choriocarcinoma in men with testicular germ cell tumors via direct stimulation of the TSH receptors

• TSH mediated hyperthyroidism is when there is a pituitary adenoma producing TSH.  Therapy is directed at removing the tumor

Hyperthyroidism• Thyroiditis is a group of

heterogenous disorders that result from inflammation of thyroid tissue with transient hyperthyroidism

• Thyroiditis has hyperthyroid phase, then hypothyroid phase and then a recovery of thyroid function

• Exogenous and ectopic hyperthyroidism occurs from taking too much thyroid hormone or it being produced by other parts of the body.

• Exogenous thyroid hormone can be produced by struma ovarii, which is from a functioning ovarian neoplasm.

Hyperthyroidism• Thyroid hormone effects almost

every organ system in the body.

• Skin-hyperthyroidism causes increased sweating due to increased caloric burning

• Hyperthyroidism causing softening of nails, thinning of hair, and can cause hyperpigmentation

• Stare and lid lag occur in patients with hyperthyroidism because of sympathetic overactivity

• Patients with graves disease can get exophthalmus because of inflammation of the extraocular muscles and orbital fat and connective tissue.

Hyperthyroidism • Hyperthyroid patients have lower serum total and HDL

cholesterol

• Hyperthyroid patient can have impaired glucose tolerance if untreated

• Hyperthyroidism can result in lower serum cortisol concentrations

• Dyspnea can occur with hyperthyroidism because oxygen consumption and CO2 production increase

• Can be tracheal obstruction due to large goiter

• Respiratory muscle weakness can cause dyspnea with hyperthyroidism

Hyperthyroidism• Weight loss with hyperthyroidism is due

to increased metabolic rate and increased gut motility.

• Dysphagia may occur because of goiter

• RBC mass index is increase with hyperthyroidism

• May have a normochromic normocytic anemia

• Hyperthyroidism can be associated with ITP

• Urinary frequency and nocturia are common with hyperthyroidism

• Woman with hyperthyroid may see high serum estradiol, high LH, and may get oligomenorrhea and anovulatory infertility

Hyperthyroidism• Thyroid hormone stimulaters bone reabsorption, bone loss

• May see increased urinary calcium excretion

• Hyperthyroidism can cause psychosis, agitation and depression

• Treatment of hyperthyroidism includes beta blockers, PTU or methimazole, or radioactive iodine

• Beta Blockers are for symptomatic treatment of hyperthyroidism

• PTU or methimazole are thyroid hormone antagonists

• Radioactive iodine is indicated for graves disease

• Surgical removal of thyroid gland is an option if necessary

Hypothyroidism• Several different causes of

hypothyroidism

• Primary hypothyroidism is when there is decreased secretion of T3 and T4 which results in a increase int TSH secretion

• Chronic autoimmune (Hashimoto's) Thyroiditis- most common cause of hypothyroidism.  When there is cell and antibody mediated destruction of thyroid tissue

• Iatrogenic Hypothyroidism-caused by thyroidectomy radio iodine treatment, or external radiation and there is less secretion of T3 and T4 as a result of it

Hypothyroidism• Iodine related hypothyroidism-excess or iodine deficiency can

cause hypothyroidism.  Iodine excess causes the inhibition of iodide organification from T4 to T3 synthesis.  Iodine deficiency causes the inability to synthesize thyroid hormone.

• Drugs such as PTU and methimazole can cause hypothyroidism. Lithium, Amiodarone and Ethionamide have been known to cause hypothyroidism.

• Infiltrative disease such as fibrous thyroiditis, hemochromatosis, scleroderma, leukemia, and cystinosis are rare causes of hypothyroidism

• Hypothyroidism in infants and children are caused by agenesis and dysgenesis of the thyroid

Hypothyroidism• Transient hypothyroidism can

be caused by post partum thyroiditis, subtotal thyroidectomy, or patients post radioactive iodine therapy with Graves disease

• Secondary Hypothyroidism is caused by lack of TSH secretion from the anterior pituitary gland

• Tertiary (Central) is caused by lack of TRH secretion form the hypothalamus

• Hypothyroidism affects essentially every organ system

Hypothyroidism• Hypothyroidism causes decreased sweating, skin

discoloration, hair to be coarse, non pitting edema (myxedema), vitiligo, and alopecia

• Hypothyroidism cans cause periorbital edema

• Hypothyroidism can cause normochromic normocytic anemia

• Hypothyroidism causes decreased cardiac output and reduction of heart rate and cardiac contractility. Hypertension can be caused from an increased in peripheral vascular resistance.  Increased cholesterol can be seen from decreased cholesterol metabolism

Hypothyroidism• Fatigue, shortness of breath on

exertion and rhinitis can be caused by respiratory muscle weakness with hypothyroidism

• Hypothyroidism causes decreased gut motility, constipation, and decreased taste sensation, and gastric atrophy

• Hypothyroidism can cause oligomenorrhea, amenorrhea, or hypermenorrhea.  This can lead to infertility.  Decreased libido, erectile dysfunction, and delayed ejaculation are possible in hypothyroidism

• Hypothyroidism left untreated can cause hashimotos encephalopathy, myxedema coma, and carpal tunnel syndrome

Hypothyroidism• Hypothyroidism can also

cause joint pain, aches, and stiffness.  There is an increased incidence of gout with hypothyroid patients.

• Hypothyroidism can cause hyponatremia

• Standard treatment of hypothyroidism is replacement therapy.  Synthetic thyroxine (T4) or combination T3 and T4 therapy. There is also T3 alone therapy