benign, osteoclast illness; vascular and filled with osteoclast -

Disorders of Ca metabolism Flashcards by k k

PTH effects

directly on kidney/bone; indirect on GI via vit D

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which form of vitamn D comes from animal vs plants

D3 from animals/we make in skin

- D2 from plant source (also has molecules inhibiting absorption)

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major vitamin D store

25 hydroxyvitamin D– fat soluble— big reservoir

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is hydroxylation regulated

No; based on mass effect

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what regulates creation of 1, 25 (OH)2 vit D

PTH

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parathyroid disorders vs vitamin D disorders

vitamin D disorders: Ca and phosphate go in same direction since it increases Ca and phosphate absorption
parathyroid disorders: moves Ca and P in opposite directions

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vit D actions

increase Ca and P absorption

- at higher leves, increases bone resorption

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Calcitonin

smaller hormone reducing Ca by reducing osteoclastic activity mainly

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how do we regulate serum Ca/detect low Ca

Parafollicular C cells/parathyrod cells/renal tubular cells all have Ca sensor receptor– signals to inside of cell what level of Ca is

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Hypercalcemia disorders

primary hyperparathyroidism
hypercalcemia of malignancy
granulomatous disorders (express 1alpha hydroxylase enzyme–so high 1, 25 vit D)
vit D/A intoxication
hyperthyroid
thiazide diuretics
Milk-Alkali syndrome
immobilization
adrenal insufficiency
acute renal failure
family hypocalciuric hypercalcemia

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most common hypercalcium disorder

primary hyperparathyroidism,

hypercalcemia of malignancy

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what do you order after see high Ca to help with diagnosis

PTH–

PTH elevated in hyperparathyroidism and low in all other except familial hypocalciuric hypercalcemia
low PTH– more likely malignancy

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brown tumors

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hyperparathyroidism causes

85% due to adenoma and the other 3 are atrophied
- 15% due to hyperplasia–usually familial and 4 glands affected
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clinical features of primary hyperparathyroidism

> 50% asymptomatic
sk disease
kidney disease
GI disease
psych disease
(Bones, Stones, Groans, Moans)
arthritis, muscle weakness, Band Keratopathy, HTN , anemia

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most common sxs of primary hyperparathyroidism

NO SXS!!

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Osteoclastoma

benign “brown tumor”

- severe hyperparathyroidism–once tumor removed, osteoclast dies and spot filled in

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Band keratopathy

band of Ca deposition of cornea medially/laterally– circumferential

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Primary hyperparathyroidism

elevated serum Ca
low serum Phosphate
elevated PTH (nl, midnl or elevated)

hos often familial vs sporadic HPT

90% sporadic (can be hyperplastic)

10% familial (can be hyperplastic)

familial cases of HPT

Familial HPT, MEN 1, MEN 2

MEN1-

pituitary tumors (multiple), pancreatic islet tumors (multiple), parathyroid hyperplasia
germline mutation in Menin gene

MEN2

medullary thyroid carcinoma (more aggressive)

pheochromocytoma
parathyroid hyperplasia
mutaiton in Ret gene (GDNF receptor)–abnormally expressed

treat HPT

surgery – adenoma- (1 gland)– minimally invasive
for hyperplasia remove 3 1/2 and can leave insitu or removed and - reimplanted to be more available if it becomes overactive in future
Calcimimetic Drug (Cinacalcet): not curative, but f not good surgical candidate
Anti-resorptive Bone Drug( bisphosphonate, denosumab)

Secondary hyperparathyroidism

elevated PTH in response to stimuli--low Ca orhigh serum P or low vitamin D - PTH elevated, but Ca low or low nl; phos high or high nl

Hypercalcemia of Malignancy

- Lung Canver (sq cell esp) - Breat Cancer - Head and neck - Kidney -Bladder - Pancreatic Ovarian Multiple Myeloma Lymphoma--express alpha hydroxylase--convert vit D to active form-- hyperabsorb Ca

hypercalcemia mediators

``` in malignancy due to PTH related Peptide - TGFbeta -TNF Interleukin 1, 6 TANK-L DKK-1 1, 25 (OH)2 vit D ```

PTHrp

- protein made by gene expressed in placenta, lactating breasts, skin - possibly role in Ca crossing placenta and transporting Ca from maternal circulation to milk - first 13 amino acids the same as PTH, this is the part that binds to the receptor

Hypercalcemia of malignancy

high Ca, low PTH, high PTH-RP or other mediators (1, 25, hydroxy vit D)

Familial hypocalciuric hypercalcemia

- inactivating mutations in Ca sensor receptor, so it doesn't sense Ca levels--PT just continues to make PTH and kidneys continue to hold onto Ca - elevated Ca (mild) - mild elevated serum PTH - decreased Urine Ca and low Ca/Creatinine ratio (

treatment for Familial hypocalciuric hypercalcemia

NOTHING--not harmful

Causes of hypocalcemia

vitamin D deficient, hypoparathyroidism, pseudohypoparathyroidism, hypomagnesemia, renal failure, liver failure, acute pancreatitis, hypoproteinemia

most common hypocalcemia cause

vitamin D deficiency

Labs in hypocalcemia

- - elevated PTH, except for hypoparathyroidism(low)

how much Ca bound to Ca

- 50% bound to protein - 50% free/ionized - if low Ca in hospital, most likely due to low serum proteins

what to consider on hospitalized pt with low Ca

- most often due to low serum proteins, so do corrected serum total calcium - add 0.8 mg/dl to total Ca for every 1g/dl Albumin is

sxs of hypocalcemia

paresthesias( lips/fingers), muscle cramps, muscle weakness, Chvostek's Sign/Trousseau's sign (both when more recent) -may have sxs if acute but if chronic may have few sxs

Trousseau's sign

sign of acute hypocalcemia-- when putting on BP cuff, will have carpopedal spasm

Chvostek's Sign

when tapping facial nerve in someone who has hypocalcemia, corner of lip will twitch

Vit D disorders

- Acquired deficiency (poor intake/inadequate sunlight) - Acquired 1,25(OH)2 vit D def (renal disease, hypoparathyroidism) - Congenital 1 alpha hydroxylase deficiency -- "Vit D dependent Ricket's Type 1: - Congenital Vitamin D receptor Deficiency - Vit D dependent Rickets Type 2 --give enough vit D will responsd

Labs on vit D deficiency

low Ca, Low, P, low 25 OH vit D elevated PTH Alk phos up if osteomalacia

Pseudofracture

not actual fracture--demineralizaiton where artery crosses bone - commonly tibia, femoral neck "Milkman's fracture"

treat vit D def

- replete with high doses vitamin D then maintain on 1000 units a day

hypoparathyroidism

low Ca, high P, low PTH

spontaneous hypoparathyroidism in young ppl

- autoimmune, oft associated with adrenal insufficiency and mucocutaneous candidiasis due to T cell immunodeficiency

pseudohypoparathyroidism

- inability to respond to PTH on membrane bound receptor. Have inactivating mutation in alpha Gs subunit--PTH can bind but no signalling - oft associated with Albright's Hereditary Osteodystrophy: shortnening 4/5th metacarpals (but can occur without pseudohypoparathyroidism)

labs on Pseudohypoparathyroidism

- low Ca - high P - high PTH -