Disorders of Calcium Metabolism

Question 1

Calcium distribution

Answer 1

• Bones & teeth (~99%)
• ICF (~1%)
• ECF (<1%)

Question 2

Calcium Sensor Receptor activation effects

Answer 2

Parathyroid Cell -PTH Secretion Parafollicular C-Cell -Calcitonin Secretion Renal Tubular Cell -Calcium Excretion

Question 3

Primary Hyperparathyroidism Classification

Answer 3

• Adenoma85%
• Hyperplasia15%
• Carcinoma< 1%

Question 4

Primary Hyperparathyroidism Clinical Features

Answer 4

-Asymptomatic (> 50%)
-Skeletal Disease
-Kidney Disease
-Gastrointestinal Disease
-Psychiatric Disease
-Band Keratopathy
(Bones Stones Groans Moans)

Question 5

Signs of Hyperparathyroidism

Answer 5

• Brown Tumor (Osteoclastoma)
• Osteitis Fibrosa Cystica
• Chondrocalcinosis
• Band Keratopathy

Question 6

Lab findings in Primary Hyperparathyroidism

Answer 6

Inc Serum Calcium
Dec Serum Phosphate
Inc Serum PTH

Question 7

Genetic causes of Primary Hyperparathyroidism

Answer 7

Sporadic90% 
Familial10% 
-Familial HPT 
-MEN I 
-MEN IIA

Question 8

MEN 1 features & mutation

Answer 8

• Pituitary tumors
• Pancreatic Islet Tumors
• Parathyroid Hyperplasia
• Germline Mutation: Menin Gene

Question 9

MEN 2a features & mutation

Answer 9

• Medullary Thyroid Carcinoma
• Pheochromocytoma
• Parathyroid Hyperplasia
• Germline mutation: RetGene (GDNF receptor)

Question 10

Primary Hyperparathyroidism Treatment

Answer 10

• Surgery
• CalcimimeticDrug (Cinacalcet)
• Anti-ResorptiveBone Drug (Bisphosphonate, Denosumab)

Question 11

Most common causes of hypercalcemia

Answer 11

1. Primary Hyperparathyroidism

2. Hypercalcemia of malignancy

Question 12

WHEN DO you find increased PTH

Answer 12

FHH & primary hyperparathyridism

Question 13

Hypercalcemia of Malignancy Mediators

Answer 13

PTH Related Peptide (PTH-RP)

Question 14

Lab findings in Hypercalcemia of Malignancy

Answer 14

Inc Serum Calcium
Low Serum PTH
Inc Serum PTH-RP

Question 15

Familial Hypocalciuric Hypercalcemia lab findings

Answer 15

Inc Serum Calcium (mild)
High Serum PTH (mild)
Low Urinary Calcium (defective receptor/excretion in kidney)
Low Urine Calcium / Creatinine Clearance Ratio

Question 16

Hypocalcemia Causes

Answer 16

Vitamin D Deficiency
Hypoparathyroidism (only one w/ low PTH)
Pseudohypoparathyroidism
Hypomagnesemia 
Hypoproteinemia**

Question 17

Corrected Serum Total Calcium method

Answer 17

Add 0.8 mg/dl to total Calcium for every 1 g/L Albumin is < 4.0 g/L

Question 18

Hypocalcemia Clinical Features

Answer 18

Paresthesias
Muscle Cramps
Muscle Weakness
Chvostek’s Sign
Trousseau’s Sign

Question 19

Major Storage Form of Vitamin D

Answer 19

25 OH Vitamin D

Question 20

Vitamin D Disorders

Answer 20

• Acquired Vitamin D Deficiency (Intake probs, no sun)
• Acquired 1,25 (OH)2 Vitamin D Deficiency (Renal Disease Hypoparathyroidism)
• Congenital 1 Alpha Hydroxylase Deficiency “Vitamin D Dependent Rickets Type 1”
• Congenital Vitamin D Receptor Deficiency “Vitamin D Dependent Rickets Type 2”

Question 21

Nutritional Vitamin D Deficiency Lab findings

Answer 21

Low Serum Calcium
 low Serum Phosphate 
highSerum Alkaline Phosphatase 
high Serum PTH 
low Serum 25 (OH) Vitamin D
low urine Calcium

Question 22

Clinical features of Vit D deficicny

Answer 22

Osteomalacia –Pseudofracture

Question 23

Hypoparathyroidism Laboratory Features

Answer 23

Low Serum Calcium
High Serum Phosphate
Low Serum PTH

Question 24

Pseudohypoparathyroidism Causes

Answer 24

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

Question 25

Pseudohypoparathyroidism Laboratory Features

Answer 25

• low Serum Calcium
• high Serum Phosphate
• high Serum PTH
• Short 4th + 5th Metacarpals (Albright’s Hereditary Osteodystrophy)