E2L25 Endocrine: Parathyroid Pathoma Flashcards
What cells produce parathyroid hormone and what are the effects of the hormone?
Free serum Ca triggers the production and release of PTH by Chief Cells.
PTH increases activity of osteoclasts to release Ca and Ph
Activates Vit D to increase absorption of Ca and Ph
Acts on kidney to increase Ca reabsorption but decrease Ph reabsorption
Why is it significant that Ph is lost in the urine from PTH?
PTH increases Ca & Ph from the bone and the intestines. Losing only Ph in the kidney allows an increase in free ionized Ca in the blood.
Patient is found to have a parathyroid adenoma that produces PTH. What are the consequences of this disease?
High PTH causes hypercalcemia which can be asymptomatic or cause problems.
Nephrolithiasis
Nephrocalcinosis–metastatic calcification of renal tubules
CNS disturbances–seizures, depression
Constipation, PUD, acute pancreatitis
Osteitis fibrosa cystica–resorption of bone leading to fibrosis and cystic spaces
What lab findings will be present with primary hyperparathyroidism?
High serum PTH, Ca, AP (from osteoblast activity)
Low serum phosphate
High urine cAMP
What is the most common cause of secondary hyperparathyroidism and explain how it works and what the labs would look like?
Renal insufficiency
This causes a decrease in the Ph excretion and thereby an increase in serum Ph. This binds free Ca and activates the parathyroid glands to increase PTH. PTH stimulates the bone to resorb.
Labs: Increased Ph, PTH, AP
Decreased Ca
Patient is found to have an elevated serum PTH. They also have high serum Ca, low Ph, high urine cAMP and high AP. They are showing Sx from the hypercalcemia. What is the likely diagnosis?
Primary hyperparathyroidism
Obvious hyperparathyroidism because of the elevated PTH and the abnormally high Ca
Most common cause is a parathyroid adenoma
If the Ca and Ph were inverted (High Ph and low Ca) then it would be a secondary hyperparathyroidism likely caused by kidney insufficiency
Patient has numbness and tingling especially around the mouth. As you take their BP you notice muscle spasms and tapping on their jaw elicits spasms. What is going on? What are these signs called?
All signs of low Ca
Trousseau: tetany/spasms when taking BP
Chvostek: spasms when tapping facial nerve
What are the causes of hypoparathyroidism and the labs that would be seen?
Causes: autoimmune damage to the gland, surgical excision, DiGeorge Syndrome (failure to form 3rd & 4th pharyngeal puches)
Labs: low PTH and low serum Ca
Patient is found to have low serum Ca despite high levels of PTH. What is this condition, the cause, and associated S/Sx?
Having low Ca despite high PTH is a sign that the tissues are not responding to the PTH. This is called pseudohypoparathyroidism. Caused by a defect in the Gs coupled receptor in the tissues.
Other SSx are short stature and short 4th & 5th digits.
