Disorders of the Parathyroid and Calcium Regulation

what is hyperparathyroidism?

excessive production/release of PTH

what is the #1 cause of ↑Ca2+?

primary hyperparathyroidism

what is the #1 cause of primary hyperparathyroidism?

chief cell adenomas

what are 2 potential causes of secondary hyperparathyroidism?

Calcium/Vit D deficiency

Chronic kidney disease (CKD)

what is the pathophysiology behind CKD causing secondary hyperparathyroidism?

Lack of 1-α-hydroxylase (can’t activate vit D)

what can prolonged 2° hyperparathyroidism lead to? why?

tertiary (3°) disease

Prolonged ↑PTH due to ↓ Ca2+ → ↑Ca2+

what is the clinical presentation of hyperparathyroidism in a large portion of patients?

asymptomatic

in primary disease what would the intact PTH and serum calcium be?

iPTH - ↑

calcium - ↑

in secondary disease what would the intact PTH and serum calcium be?

iPTH - ↑

calcium - ↓

how else can you assess calcium other than serum? what does it mean if levels are low?

urinary assessment (24 hr)

familial hypocalciuric hypercalcemia

what are the 3 options for parathyroid imaging?

Ultrasound

Nuclear scanning (sestamibi-iodine subtraction scanning)

MRI > CT

how do you treat "mild" asymptomatic hyperparathyroid causes?

Try to "control" the hypercalcemia - Avoid thiazide diuretics & calcium-containing antacids

Follow-up/Surveillance

why would it be beneficially to do an open neck exploration on a patient with a parathyroid problem?

allows to visibly inspect all 4 glands and able to differentiate if its multiple glands or singular involved; normally one or two involved so allows to save the good glands instead of taking them all out

what are medical management options for hyperparathyroidism?

fluids

bisphosphonates

vitamin D

cinacalcet (sensipar®)

what is hypoparathyroidism?

Reduced or absent synthesis of PTH

Synthesis of biologically inactive PTH

PTH "resistance"

what is the #1 etiology of hypoparathyroidism?

glandular damage/removal

what is the net result of Ca2+ and PO43- in hypoparathyroidism? why?

↓ Ca2+ & ↑ PO43-

Regardless of etiology, PTH is unable to maintain Ca2+ levels

what is pseudohypoparathroidism?

Group of disorders characterized by ↓ sensitivity of “end-organs” to PTH - “PTH-resistant”

PTH levels actually elevated (↑)

Usually due to PTH receptor mutations

what patients need further evaluated for hypocalcemic/PTH d/o?

Only pts with ↓ ionized Ca2+ levels (Ø ↓ total Ca2+ )

other diagnostic findings for hypoparathyroidism are not necessarily ordered as a part of work up however what ECG finding might you see?

prolonged QT

everyone with hypoparathyroidism needs treated t/f

false

chronic symptomatic patients with hypoparathyroidism need lifelong therapy that consists of ?

Calcium supplements

Vitamin D

rhPTH (Natpara®/Teriparatide (Forteo®))

what is the main emergent therapy for post op tetany?

IV calcium gluconate

what is familial hypocalciuric hypercalcemia (FHH)? what is the pathophysiology?

Autosomal dominant condition

Detection of serum Ca2+ is faulty – thinks it’s ↓ which then stimulates PTH secretion

what is the clinical presentation/labs look like for FHH?

Lifelong ↑Ca2+ (Asymptomatic)

↓ Urinary Ca2+

↑PTH

what is the treatment for FHH in adults?

Condition is benign

They do NOT have “consequences” of ↑ PTH

what cancers are most likely to cause hypercalcemia?

Breast, Lung, Lymphoma, Thyroid, Kidney, Prostate, Multiple Myeloma

(BLT with a Kosher Pickle, Mustard & Mayo)

most cancers that cause hypercalcemia are due to "humoral" hyperparathyroidism explain this

Tumor secretes PTHrP & mimics 1° hyperPTH

multiple myeloma and lymphomas are types of cancer that cause hypercalcemia how?

Local “osteolytic” hypercalcemia (MM)

↑1,25(OH)2D secretion (lymphomas)

what is the treatment for hypercalcemia caused malignancy?

Aggressive hydration #1

Bisphosphonate therapy IV

furosemide