EOR endocrine part 2 Flashcards
What is the MCC of hyperthyroidism?
Graves’ disease
What is Graves’ dz?
Diffuse goiter with hyperthyroidism, exophthalmos, and pretibial myxedema
Etiology of Graves’ dz
Caused by circulating antibodies that stimulate TSH receptors on follicular cells of the thyroid
Female to male ratio of Graves’ dz
6:1
What specific physical finding is associated with Graves’?
Exophthalmos
How is the dx made of Graves’ dz?
Increased T3, T4, and anti-TSH receptor antibodies
Decreased TSH
Global uptake of I131 radionuclide
Name tx option modalities for Graves’ dz
Medical blockade: iodide, propranolol, PTU, methimazole, Lugol’s solution (potassium iodide)
Radioiodide ablation: most popular therapy
Surgical resection: bilat subtotal thyroidectomy
What are the possible indications for surgical resection in Graves’ dz?
Suspicious nodule If pt is noncompliant or refractory to medicines Pregnant A child If pt refuses radioiodide therapy
What is the major complication of radioiodide or surgery for Graves’ dz?
Hypothyroidism
How does PTU work?
Inhibits incorporation of iodine into T4/T3 (by blocking peroxidase oxidation of iodide to iodine)
Inhibits peripheral conversion of T4 to T3
How does methimazole work?
Inhibits incorporation of iodine into T4/T3 only
Define primary hyperparathyroidism
Increased secretion of PTH by parathyroid gland(s); marked by elevated calcium, low phosphorous
Define secondary hyperparathyroidism
Increased serum PTH resulting from calcium wasting caused by renal failure or decreased GI calcium absorption, rickets, or osteomalacia; calcium levels are usually low
Define tertiary hyperparathyroidism
Persistent HPTH after correction of secondary hyperparathyroidism; results from autonomous PTH secretion not responsive to the normal negative feedback due to elevated calcium levels
What are the methods of imaging the parathyroids?
Surgical operation U/s Sestamibi scan TI (technitium)- thallium subtraction scan CT scan/MRI A-gram (rare) Venous sampling for PTH (rare)
What are the indications for a localizing preoperative study?
Reoperation for recurrent hyperparathyroidism
What is MCC of primary hyperparathyroidism?
Adenoma (>85%)
What are the etiologies of primary HPTH and percentages?
Adenoma (~85%)
Hyperplasia (~10%)
Carcinoma (~1%)
What are the RFs for primary hyperparathyroidism?
FHx
Men-I
MEN IIa
Irradiation
What are the s/sx of primary HPTH hypercalcemia?
Stones: Kidney stones
Bones: bone pain, pathologic fx, subperiosteal resorption
Groans: muscle pain and weakness, pancreatitis, gout, constipation
Psychiatric overtones: depression, anorexia, anxiety
Other sx: polydipsia, wt loss, HTN, polyuria, lethargy
What is the 33-to-1 rule?
Most pts with primary HPTH have a ratio of serum chloride to phosphate greater than or equal to 33
What plain XR findings are classic for HPTH?
Subperiosteal bone resorption
How is primary HPTH diagnosed?
Labs- elevated PTH (hypercalcemia, decreased phosphorous, increased chloride)
Urine calcium should be checked for familial hypocalciuric hypercalcemia
What is familial hypocalciuric hypercalcemia?
Familial (autosomal dominant) inheritance of a condition of asymptomatic hypercalcemia and low urine calcium, with or without elevated PTH
In contrast, hypercalcemia from HPTH results in high levels of urine calcium
DDx of hypercalcemia
Calcium overdose Hyperparathyroidism Hyperthryoidism Hypocalciuric hypercalcemia Immobility/iatrogenic (thiazide diuretics) Metastasis/milk alkali syndrome Paget's disease Addison's disease/acromegaly Neoplasm Zollinger-Ellison syndrome Excessive vit D Excessive vit A Sarcoid
What is the initial medical tx of hypercalcemia (primary HPTH)?
Medical- IVF, furosemide- NOT thiazide diuretics
Although most recommend surgery for asymptomatic primary HPTH, when is it considered mandatory?
Renal insufficiency (CR decreased by 30%)
Osteoporosis
Age <50
Calcium >1 mg/dL above upper limit of nl
Hypercalciuria (>400 mg/day Ca excretion)
What is the definitive tx for primary HPTH resulting from hyperplasia?
Neck exploration removing all parathyroid glands and leaving at least 30 mg of parathyroid tissue placed in the forearm muscles
What is the definitive tx for primary HPTH resulting from parathyroid adenoma?
Surgically remove adenoma (send for frozen section) and bx all abnormally enlarged parathyroid glands
What is the definitive tx for primary HPTH resulting from parathyroid carcinoma?
Remove carcinoma, ipsilateral thyroid lobe, and all enlarged LNs
What is the definitive tx for secondary HPTH?
Correct calcium and phosphate; perform renal transplantation
What is the definitive tx for tertiary HPTH?
Correct calcium and phosphate
Perform surgical operation to remove all parathyroid glands and reimplant 30-40 mg in the forearm if refractory to medical tx
What must be ruled out in the pt with HPTH from hyperplasia?
MEN type I and MEN type IIa
What carcinomas are commonly associated with hypercalcemia?
Breast CA metastases Prostate CA Kidney CA Lung CA Pancreatic CA Multiple myeloma
