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IM Endo Calcium Bone USMLE 2

Terms

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Definition:
Disease of impaired bone mineralization
Osteomalacia


(Mineralization = Malacia)
Osteomalacia in children
Rickets
Basic etiology of Osteomalacia
(4)
Decreased Calcium absorption;

Dietary Calcium deficiency;

Vitamin D deficiency;

Hypophosphatemia
Causes of dietary Calcium deficiency
(3)*
Malabsorption syndromes;

Gastrectomy;

Dumping syndrome
Main Causes of Vitamin D deficiency
(2)
Hepatobiliary and Pancreatic diseases
(loss of bile acids or pancreatic lipase reduce absorption of fat-soluble vitamins);

Renal Osteodystrophy
Causes of Hypophosphatemia
(2)
Renal Tubular Acidosis;

Falconi's syndrome
Dx:
Bone pain, weakness, difficulty walking: broad-based waddling gait w/ short strides; thoracic kyphosis
Osteomalacia

(Rickets in children)
What do blood tests show to Dx Osteomalacia?
(3)
Labs:

1. Low - nml Calcium;

2. Low - nml Phosphate;

3. High Alk-phos
(possible high PTH)
Tx for Osteomalacia
(2)
Tx underlying disorder;

Calcium and Vitamin D supplements
Definition:
Systemic disorder resulting in a reduction of bone mass that leads to increased risk of fracture
Osteoporosis
Risk factors for Osteoporosis
(6)
Elderly Female;
Post-menopause;
Family Hx;
Smoking;
Thin body;
Sedentary lifestyle
Pathophysiology of Osteoporosis
Reduction of bone mass occurs due to an imbalance b/t bone aquisition and bone reabsorption; w/o change in the ratio of mineral to organic bone
Histology of Osteoporosis
Decreased cortical thickness and number (and size) of cancellous bone trabeculae
(especially horizontal)
When does osteoporosis usually become symptomatic?

(2) types
when Fracture occurs:

Vertebral body fracture;

Hip fracture
Dx lab blood test results for Osteoporosis
Everything is normal:

Serum Ca++ and PO4- are usu normal;
Alk-phos is normal unless there is a fracture, then it's increased
How is bone mineral density measured?
(2) Dx results
Dual X-ray Absorptiometry (DEXA) scan

T-score < -2.5 = Osteoporosis

T-score -2.5 to -1 = Osteopenia
Differential in Osteoporosis
(4)*
Malignancy;

Hyperparathyriodism;

Osteomalacia;

Padget's disease of the bone
Prevention and Tx for Osteoporosis
(4)
Dietary Calcium and Weight-bearing exercises;

Estrogen replacement therapy;

Calcitonin;

Bisphosphonates (Alendronate) w/ Vitamin D and Calcium supplements
Definition:
Chronic Dz of adult bone in which localized areas of bone becomes hyperactive, and the normal bone matrix is replaced by softened and enlarged bone
Padget's Disease of the bone
If Alkaline Phos is elevated, what is the next step?
(2)
Send GGT to determine if it is Hepatic (elevated GGT) or bone (not elevated)

or

Check to see if it is heat-labile (Bone), where hepatic is not
Histology:
Hyperactive bone turnover w/ enlarged multinucleated osteoclasts
Padgets Disease of the bone
Dx:
45-yo male is found to have an elevated alkaline phosphatase during a routine blood test. No other abnormalities were found. Further workup reveals the enzyme to be heat labile
Padget's Disease of the bone
Radiologic finding:
area of hyperlucency of the bone surrounded by a hyperdense border
Padget's Disease of the bone
Tx for Padget's Disease of the Bone for:
1. Pain relief
2. Anatomic deformity or impingement
3. to Decrease bone reabsorption
4. to assist w/ cardiac failure or neurologic deficits
1. Pain = Indomethacin

2. Deformity = Osteotomy of the bone

3. Decrease Reabsorption = Bisphosphonates

4. Assist in CardiacNeuro = Calcitonin
What is the Normal serum Calcium range?
8.5 - 10.2 mg/dL
Etiology of Hypocalcemia
(8)*
IV STRAP:
Insufficient PTH;
Vitamin D deficiency;
Sepsis / Severe Mg deficiency;
Toxins;
Rhabdomyolysis;
Albright's Osteodystrophy (Pseudohypoparathyroidism);
Pancreatitis
Osteoporosis Risk factors
(8)*
FACELESS:
Family history;
Alcohol;
Corticosteroids;
Elderly Female;
Low Calcium;
Estrogen low (Menopause);
Smoking;
Sedentary lifestyle
First sign/Sx of Hypocalcemia

Name and describe (2) other common signs seen in PE
first sign:
Circumoral Paresthesia

Chvostek's sign:
Facial muscle spasm w/ tapping of the facial nerve

Trousseau's sign:
Carpal spasm after occluding blood flow in forearm w/ BP cuff
What is seen w/ EKG for Hypocalcemia?
Prolonged QT and ST intervals


(also peaked T-waves can be seen as in HyperK)
How can Calcium correct for Hypoalbuminemia?
Adjust Calcium upward by 0.8mg/dL for each 1.0g/dL of albumin below normal
Toxins that cause low calcium
(5)*
Can Produce A Calcium Fall:
Cimetidine;
Phenytoin;
Alcohol;
Citrate;
Fluoride
Etiology of Hypercalcemia
(14)*
CHIMPANZEES:
Calcium supplementation;
Hyperparathyroidism / Hyperthyroidism;
Immobility;
Meds / Multiple Myeloma;
Padget's Dz;
Addison's Dz / Acromegaly;
Neoplasm metastasis;
Zollinger-Ellison syndrome;
Excess Vit-A;
Excess Vit-D;
Sarcoidosis or TB (granulomatous dz)
MCC of hypercalcemia


MCC for inpatient?
Primary Hyperparathyroidism


Inpatient: Malignancy
Dx:
malaise, HA, diffuse aches, dehydration, N/V, nodules on skin, cornea, conjunctiva and kidneys
Hypercalcemia

(nodules are calcifications)
Drugs that cause Hypercalcemia
(5)*
C-TALE:
Calcium supplementation;
Thiazides;
Antacid abuse;
Lithium;
Excess Vitamin D
Dx:
"Stones, bones, groans and psychiatric overtones"
Hyperparathyroidism
Tx for Primary Hyperparathyroidism patient w/ underlying cardiac failure
(drug and maintenance)
Lasix to maintain diuresis

and

Pulmonary artery pressure monitoring to avoid volume overload
Pathophysiology behind Renal Osteodystrophy
Nephron loss reduces phosphate excretion, causing hyperphosphatemia, which lowers serum calcium and increases PTH secretion
(secondary parahyperthyroidism)
(3) Bone lesions assoc w/ Secondary Hyperparathyroidism
Osteitis Fibrosa Cystica;

Adynamic Bone Dz;

Osteomalacia
Definition:
Normal bone is replaced by fibrous tissue, primitive woven bone and cysts
Osteitis Fibrosa Cystica
Dx:
bone pain, proximal muscle weakness, pruritis, soft-tissue ulcerations, diffuse soft-tissue calcifications
Secondary Hyperparathyroidism

(Renal Osteodystrophy)
Goal and Tx for Secondary Hyperparathyroidism /
Renal Osteodystrophy
(2 drugs and 2 if drugs dont work)
Goal:
Normalize calcium-phos balance

Tx:
1. Aluminum-containing antacids: reduce GI absorpt of PO4-
2. Vit-D w/ Calcitrol: inc serum Ca++ and reverse bone damage

3. Subtotal parathyroidectomy
4. Renal transplant
If patient has hypocalemia or hypophosphatemia (or both) what is the next step?
Check for Hypomagnesemia:

Ca++ and PO4- will not elevate if Magnesium is low
Dx:
Rapid transfer of Calcium into bones following removal of hyperactive parathyroid

What electolyte disorder can it cause?
Hungry Bone syndrome


can cause: Hypomagnesemia

Deck Info

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