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Flashcards in disorders of Calcium Deck (36):
1

Calcium distribution

1. Bones and Teeth (~ 99%). 2. Intracellular Compartment (~ 1%). 3. Extracellular Fluids (< 1%) -Ionized Calcium - 48%, Protein Bound Calcium - 44%

2

serum Ca limits

10.5mg/dl is upper limit and 8.5mg/dl is lower limit. At 9.0mg/dl Ca raising mechanisms are initiated. At 10.0mg/dl Ca lowering mechanisms are initiated

3

PTH effects

Increases Serum Ca: increases bone resorption, increases Ca absorption from intestines, decreases Ca excretion by kidneys, increases Vit D production by kidneys and increases phosphate excretion by kidneys

4

compare Vitamin D from skin vs diet

Skin: D3 cholecaldiferol. Diet: D2 ergocalciferol or D3 cholecalciferol

5

Vitamin D effects

Increases Serum Ca: Increases bone resorption, increases Ca absorption from intestines and increases phosphate absorption

6

Calcitonin effects

Decreases Serum Ca: decreases bone resporption

7

List hypercalcemic disorders with elevated PTH

primary hyperparathyroidism, familial hypocalciuric hypercalcemia

8

Classifications of primary hyperparathyroidism

Adenoma (85%), hyperplasia (15%), carcinoma (<1%)

9

Clinical features of primary hyperparathyroidism

>50% are asymptomatic. Skeletal dz, kidney dz, GI dz, psychiatric dz, arthritis, muscle weakness, band keratopathy, hypertension, anemia

10

Hyperparathyroidism imaging

Brown tumor- osteoclastoma. Osteitis fibrosa cystica (bones appear large and hollow). Chondrocalcinosis

11

Hyperparathyroidism physical exam findings

Band keratopathy of the eyes.

12

Primary hyperparathyroidism diagnosis

Increased serum Ca, decreased serum phosphate, increased serum PTH

13

Causes of primary hyperparathyroidism

sporadic (90%), famial (10%)- familial HPT, MENI, MENIIA

14

Components and cause of MENI

Pituitary tuors, pancreatic islet tumors and parathyroid hyperplasia. Caused by germline mutation of Menin gene

15

Components and cause of MENIIA

medullary thyroid carcinoma, pheochromocytoma and parathyroid hyperplasia. Caused by germline mutation of Ret gene (GDNF receptor)

16

Treatment of primary hyperparathyroidism

1. surgery. 2. Calcimimetic drugs (cinacalcet). 3. anti-resorptive bone drug (bisphosphanate, denosumab)

17

When is surgery recommended for primary hyperparathyroidism

Serum Calcium > 1 mg/dl Above Normal, Creatinine Clearance < 60 ml/min, BMD T-Score < -2.5 or Fragility Fracture, Kidney Stones, Age < 50 Years

18

Management of mild asymptomatic primary hyperparathyroidism

Ca and Vit D supplements. Measure Serum Ca and creatinine every 6-12 month. Measure bone density every 1-2 years

19

Secondary hyperparathyroidism

decreased calcium, increased phosphorus and/or decreased Vitamin D lead to increased PTH.

20

What is hypercalcemia of malignancy

Elevated Ca and decreased PTH in the setting of cancer

21

List mediators of hypercalcemia of malignancy

PTH related peptide, TGFBeta, TNF, Interleukin1 or 6, RANK-L, DKK-1, Vitamin D

22

Diagnosis of hypercalcemia of malignancy

elevated serum Ca, decreased serum PTH, elevated PTH-RP or other mediator

23

Treatment of hypercalcemia of malignancy

1. Promote Urine Calcium Excretion- Saline Infusion. 2. Inhibit Bone Resorption- IV Bisphosphonates, Denosumab, Calcitonin, Plicamycin. 3. Remove Calcium- Dialysis

24

What is familial hypocalciuric hypercalcemia

Mutations lead to increased PTH secretion and decreased Ca excretion. This causes increased serum Ca. Urine Ca/ Creatinine clearance ratio is <0.01

25

familial hypocalciuric hypercalcemia treatment

None needed. Avoid surgery

26

Causes of hypocalcemia

1. decreased PTH: hypoparathyroidism. 2. Vit D deficiency. 3. hypomagnesemia. 4. renal or liver failure. 5. acute pancreatitis. 6. hypoproteinemia

27

Clinical features of hypocalcemia

Paresthesias, Muscle Cramps, Muscle Weakness, Chvostek’s Sign (tapping facial nerve at masseter causes contraction of muscles of face) , Trousseau’s Sign (occlusion of brachial artery induces spasm of muscles of hand and forearm)

28

Causes of Vitamin D deficiency

1. Poor intake or sunlight. 2. Renal dz. 3. hypoparathyroidism. 4. Congenital 1-alpha hydroxylase deficiency (Vit D dependent rickets type 1). 5. congenital Vit D receptor deficiency (Vit D dependent rickets type 2)

29

Vit D deficiency labs

Decreased serum Ca, decreased Phosphate, increased alkaline phosphatase, increased PTH, decreased Vit D, decreased urine Ca

30

Signs of Vit D deficiency

osteomalacia-pseudofracture (milkmans fracture or loosers line)

31

Hypoparathyroidism labs

decreased Ca, increased phosphate, decreased PTH

32

hypoparathyroidism treatment

Ca supplements, Calcitriol, thiazide diuretics

33

Pseudohypoparathyroidism

Inactivating mutation of the Gs alpha subunit or other downstream PTH response element

34

Pseudohypoparathyroidism signs

albrights hereditary osteodystrophy (short 4th and 5th metacarpals)

35

Pseudohypoparathyroidism labs

decreased serum Ca, increased serum phosphate, increased serum PTH

36

Pseudohypoparathyroidism treatment

calcium, calcitriol, thiazide diuretics