BONE MINERAL HOMEOSTASIS

Question 1

ROLE OF MAGNESIUM IN PTH SECRETION

Answer 1

• A moderate decline in Mg –> enhance in PTH secretion
• A severe decrease in Mg –> decrease in PTH secretion
• Common causes of ↓Mg are:

1) Chronic diarrhea;
2) diuretics and
3) alcohol abuse;
4) Chronic PPI and
5) aminoglycoside use.

Question 2

FIBROLBST GROWTH FACTOR 23

IS PRODUCED BY?

ACTIONS?

Answer 2

It is produced by osteoblasts and osteoclasts.

Inhibits calcitriol pr oduction and Phosphate reabsorption in Kidney.

–> ie it decreases serum phosphate, and increases phosphate excretion in the kidney

–> also decreases calcium and phosphate absorption by the intestines

Question 3

TREATMENT OF HYPERCALCEMIA

Answer 3

Most cases are asymptomatic or may be mild.

Severe cases present with stones (nephrolithiasis); bones (bone pain, myalgias, arthralgias or fractures); abdominal groans (abdominal pain, nausea, vomiting), thrones (sits on throne for polyuria) and psychiatric overtones (fatigue, depression, anxiety, sleep disturbances)

Treatment: KNOW THESE

Furosemide and saline infusion

Bisphosphonates

Calcitonin

Parathyroidectomy, if patient is symptomatic.

Question 4

TREATMENT OF OSTEOPOROSIS

Answer 4

Treatment:

Stop smoking, alcohol abuse and corticosteroid

HRT–in symptomatic perimenopausal period

Calcium & Vitamin D supplimentation

Bisphosphonates

SERMs

Teriparatide

Question 5

DRUG THAT CAUSES EROSIVE ESOPHAGITIS as an AE

Answer 5

ETIDRONATE (is a bisphonsphate)

Question 6

MOA OF ETIDRONATE

Answer 6

MOA:

They inhibit osteoclastic activity via↓ farnesyl pyrophosphate synthesis by disrupting mevalonate pathway ↓ osteoclast H+ ATPase.

1) Reduce resorption and 2) helps formation of hydroxyapatite.

Question 7

DRUG THAT CAUSES OSTEONECROSIS OF JAW + INCRASES RISK OF FRACTURES (ie causes osteomalacia)

Answer 7

ETIDRONATE IF TAKEN FOR MORE THAN 12 MONTHS