Disorders of Calcium Metabolism Flashcards
Calcium distribution
- Bones & teeth (~99%)
- ICF (~1%)
- ECF (<1%)
Calcium Sensor Receptor activation effects
Parathyroid Cell -PTH Secretion Parafollicular C-Cell -Calcitonin Secretion Renal Tubular Cell -Calcium Excretion
Primary Hyperparathyroidism Classification
- Adenoma85%
- Hyperplasia15%
- Carcinoma< 1%
Primary Hyperparathyroidism Clinical Features
-Asymptomatic (> 50%)
-Skeletal Disease
-Kidney Disease
-Gastrointestinal Disease
-Psychiatric Disease
-Band Keratopathy
(Bones Stones Groans Moans)
Signs of Hyperparathyroidism
- Brown Tumor (Osteoclastoma)
- Osteitis Fibrosa Cystica
- Chondrocalcinosis
- Band Keratopathy
Lab findings in Primary Hyperparathyroidism
Inc Serum Calcium
Dec Serum Phosphate
Inc Serum PTH
Genetic causes of Primary Hyperparathyroidism
Sporadic90% Familial10% -Familial HPT -MEN I -MEN IIA
MEN 1 features & mutation
- Pituitary tumors
- Pancreatic Islet Tumors
- Parathyroid Hyperplasia
- Germline Mutation: Menin Gene
MEN 2a features & mutation
- Medullary Thyroid Carcinoma
- Pheochromocytoma
- Parathyroid Hyperplasia
- Germline mutation: RetGene (GDNF receptor)
Primary Hyperparathyroidism Treatment
- Surgery
- CalcimimeticDrug (Cinacalcet)
- Anti-ResorptiveBone Drug (Bisphosphonate, Denosumab)
Most common causes of hypercalcemia
- Primary Hyperparathyroidism
2. Hypercalcemia of malignancy
WHEN DO you find increased PTH
FHH & primary hyperparathyridism
Hypercalcemia of Malignancy Mediators
PTH Related Peptide (PTH-RP)
Lab findings in Hypercalcemia of Malignancy
Inc Serum Calcium
Low Serum PTH
Inc Serum PTH-RP
Familial Hypocalciuric Hypercalcemia lab findings
Inc Serum Calcium (mild)
High Serum PTH (mild)
Low Urinary Calcium (defective receptor/excretion in kidney)
Low Urine Calcium / Creatinine Clearance Ratio
Hypocalcemia Causes
Vitamin D Deficiency Hypoparathyroidism (only one w/ low PTH) Pseudohypoparathyroidism Hypomagnesemia Hypoproteinemia**
Corrected Serum Total Calcium method
Add 0.8 mg/dl to total Calcium for every 1 g/L Albumin is < 4.0 g/L
Hypocalcemia Clinical Features
Paresthesias Muscle Cramps Muscle Weakness Chvostek’s Sign Trousseau’s Sign
Major Storage Form of Vitamin D
25 OH Vitamin D
Vitamin D Disorders
- 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”
Nutritional Vitamin D Deficiency Lab findings
Low Serum Calcium low Serum Phosphate highSerum Alkaline Phosphatase high Serum PTH low Serum 25 (OH) Vitamin D low urine Calcium
Clinical features of Vit D deficicny
Osteomalacia –Pseudofracture
Hypoparathyroidism Laboratory Features
Low Serum Calcium
High Serum Phosphate
Low Serum PTH
Pseudohypoparathyroidism Causes
Inactivating mutation of the GS alpha subunit or other downstream PTH response element
