Parathyroid Pathology Flashcards
What are the two cell types that make up the parathyroid?
Chief cells
Oxyphill cells
What hormone do Chief cells secrete?
PTH
What makes Oxyphill cells pink?
Abundance of mitochondria
What are the main functions of PTH?
Increase renal resorption of Ca
Increase urinary PO4 excretion
Increase conversion of Vitamin D –> Dihydroxy form
Release Ca and PO4 from bone
What is the most common cause of Primary Hyperparathyroidism?
Parathyroid Adenoma
What is the most common cause of asymptomatic hypercalcemia?
Parathyroid Adenoma
What molecular defects are found in sporadic Parathyroid Adenomas?
Cyclin D1
MEN1
What molecular defects are found in familial Parathyroid Adenomas?
MEN1
RET
How many glands does Parathyroid Adenoma typically affect?
1 of the 4
Morphology = well-circumscribed, hypercellular (mostly Chief) mass in a single parathyroid gland
Parathyroid Adenoma
What disease causes all 4 glands of the parathyroid to be enlarged, even if they are asymmetrically enlarged?
Parathyroid Hyperplasia
What do the cells of Parathyroid Carcinoma look like?
Normal parathyroid gland cells
How is the Dx of Parathyroid Carcinoma made?
By the presence of invasion or metastases
What are the Sx’s of Primary Hyperparathyroidism?
Bones, Stones, Groans (GI), and Moans (Psych)
What is the MOA for Secondary Hyperparathyroidism?
Compensatory hypersecretion of PTH due to prolonged hypocalcemia
What are some EX’s of Secondary Hyperparathyroidism?
Chronic renal failure
Poor dietary Ca intake
Steatorrhea
Vitamin D deficiency
Morphology = Hyperplastic parathyroid gland with metastatic calcifications seen in lungs, heart, stomach, and blood vessels
Secondary Hyperparathyroidism
What is Calciphylaxis?
Vascular calcification –> ischemic damage to the skin and other organs
What is the MOA of Tertiary Hyperparathyroidism?
Hypersecretion of PTH after the cause of the prolonged hypocalcemia (2˚ Hyperparathyroidism) has been corrected
What is the Tx for Tertiary Hyperparathyroidism?
Surgical removal (leave a little for normal physiologic function)
What is the Tx for Secondary Hyperparathyroidism?
Vitamin D supplements
PO4 binders
What type of inheritance pattern does Familial Hypocalciuric Hypercalcemia have and what is the mutated gene?
AD
Calcium-Sensing Receptor gene (CASR)
What are some causes of hypoparathyroidism?
Hypercalcemia of malignancy Vitamin D toxicity Immobilization Thiazide diuretics Granulomatous disease (Sarcoidosis)
What are Brown Tumors?
Microfractures in bone –> secondary hemorrhage –> influx of macrophages and repair with fibrous tissue –> formation of a mass
What is Osteitis Fibrosa Cystica?
Increased osteoclast activity, peritrabecular fibrosis, and cystic brown tumors
What is Nephrocalcinosis?
Calcification of renal interstitium and tubules
What is the most common cause of symptomatic hypercalcemia
Hypercalcemia of malignancy
The most common types of tumors causing Hypercalcemia of Malignancy are located where?
Lung
Breast
Head/Neck
Kidneys
What hormone typically causes the hypercalcemia in Hypercalcemia of Malignancy?
PTH-Related Peptide (PTHrP)
What are the main 4 lab values used to Dx Hypercalcemia of Malignancy?
Hypercalcemia
Elevated PTH
Hypophosphatemia
What is the most common cause of hypoparathyroidism?
Surgically induced
What autoimmune issues are associated with hypoparathyroidism?
Chronic mucocutaneous candidiasis
Primary Adrenal Insufficiency (AKA Autoimmune Polyendocrine Syndrome Type-1 [APS1])
What mutation is associated with the inherited form of hypoparathyroidism and what type of inheritance pattern does it follow?
GofF of CASR gene
AD
Sx’s = tetany, mental status change, prolonged QT interval, dental abnormalities in kids
Hypoparathyroidism (hypocalcemia)
What disease causes congenital absence of the parathyroid glands?
DiGeorge syndrome
What disease is due to end-organ resistance to PTH?
Pseudohypoparathyroidism
What would the lab values be for Ca and PO4 in Pseudohypoparathyroidism?
Hypocalcemia
Hyperphosphatemia
What would the lab values be for PTH in Pseudohypoparathyroidism?
Normal or elevated PTH
In pts with Pseudohypoparathyroidism, which other hormones might the pts have end-organ resistance to?
TSH
FSH/LH
