Endocrine Flashcards
Secondary (pituitary gland) and tertiary (hypothalamic) HPA endocrine disorders have labs in the same OR opposite direction
SAME direction
Ex: TSH-secreting pituitary adenoma = increased TSH and free T3/T4
Cushing’s disease (2/2 pituitary adenoma) = increased ACTH and increased cortisol levels
Primary endocrine disorders (d/o where target organ = main problem) have labs in same direction or opposite direction
Have labs in OPPOSITE direction
Ex 1: Graves, toxic goiters, & toxic thyroid adenoma = increased free T3/T4 but DECREASED TSH - free T3/T4 feeds back on Hypothalamus & pituitary to shut down TRH/TSH release
Ex 2: Hashimoto’s thyroiditis = decreased free T3/T4 and INCREASED TSH
What is the best test for screening thyroid function
TSH levels
Best initial test for suspected thyroid disease.
Also used to follow pt on thyroid hormone tx - low TSH - decrease dose of levothyroxine, high TSH = increase dose of levothyroxine
When do you order free T4 level?
Orderd when TSH is abnormal to determine thyroid hyperfunction or hypofunction and in conjunction with TSH levels to monitor Grave’s
Antibodies present in Hashimoto’s thyroiditis
Anti-thyroid peroxidase Ab
Anti-thyroglobulin Ab
Ab present in Grave’s disease
Thyroid stimulating Ab (TSH receptor Ab)
RAIU Test- diffuse uptake
Grave’s disease
RAIU Test - Decreased uptake
Thyroiditis (hashimoto’s)
RAIU Test - Hot nodule
Toxic adenoma
RAIU Test - Multiple nodules
Toxic multinodular goiter
RAIU Test - cold nodules
Rule out malignancy
Elevated TSH
Subsequent low FT4
Primary hypothyroidism
Elevated TSH
Subsequent high FT4
Secondary TSH-mediated hyperthyroidism
Elevated TSH
Subsequent normal FT4
Subclinical hypothyroidism
Low TSH
Low FT4
Secondary or tertiary hypothyroidism (rare) - usually pituitary issue or drug-induced
Low TSH
High FT4
Primary hyperthyroidism, thyrotoxicosis (target organ pumping out too much FT4) –> check RAIU to identify cause - diffuse uptake = Grave’s disease
Management of subclinical hypothyroidism
Subclinical = High TSH, normal FT4
Tx: Levothyroxine IF pt develops hyperlipidemia, TSH > 20, or hypothyroid symptoms
Etiologies Hypothyroidism
Iodine deficiency Hashimoto's thyroiditis Postpartum thyroiditis Pituitary or hypothalamic hypothyroidism Cretinism Reidel's thyroiditis
Etiologies hyperthyroidism
Grave's disease Toxic multi-nodular goiter TSH-secreting pituitary adenoma Excess intake of T3, T4 Iatrogenic thyrotoxicosis
CP Hypothyroidism
Decreased BMR Cold intolerance Dry, thick, rough skin Loss of outer 1/3 eyebrow Goiter Nonpitting edema (myxedema) Hypoactivity (fatigue, sluggish, memory loss, depression) Constipation, anorexia Bradycardia Menorrhagia Hypoglycemia
CP Hyperthyroidism
Increased BMR Heat intolerance Weight loss (despite inc appetite) Diarrhea, hyper-defecation Tachycardia, palpitations, high output heart failure Scanty periods, gynecomastia Hyperglycemia Skin: warm, moist, soft, fine hair, alopecia, easy bruising
Hyperactivity (anxiety, fine tremors, nervousness, weakness, increased SANS)
Cretenism
Congenital hypothyroidism - 2/2 maternal hypothyroidism or infant hypo-pituitarism
Cretenism CP
Macroglossia, hoarse cry, coarse facial features, umbilical hernia, weight gain
Mental development abnl may develop if not corrected
Etiology hypercalcemia
> 90% of cases caused by primary hyperparathyoidism or malignancy
Familial hypercalciuric hypercalcemia
Vitamin D excess
