Musculo/Derm 3 Flashcards
What is Parathyroid hormone (PTH)?
A hormone that increases blood calcium levels by promoting phosphate excretion and stimulating osteoblast activity.
What is the treatment for Rickets and Osteomalacia?
Vitamin D and Ca supplementation.
What is the best indicator for Vitamin D status? Why?
Serum 25-OH Vit D
It has a long half-life and liver production is not regulated by PTH.
What is the storage form for Vitamin D?
25-OH Vitamin D.
What is Paget’s Disease also called?
Osteitis Deformans.
Is Paget’s disease a focal or widespread disorder?
Focal.
Paget’s Disease is common in what age group?
Older patients.
What is the mechanism of Paget’s Disease of the bone?
Excessive bone remodeling, believed to be due to abnormal osteoclasts.
What are the 3 phases of Paget’s disease?
Initial (Osteolytic), Mixed (Osteolytic-osteoblastic), Final (Osteosclerotic).
What occurs in the Osteosclerotic phase of Paget’s disease?
Bone formation dominates and hypervascularity of bone occurs.
What is the hallmark of Bone morphology in Paget’s disease?
Mosaic pattern of lamellar bone.
What is the most common complication of Paget’s disease?
Chalkstick fracture.
What are 7 clinical features of Paget’s disease?
Chalkstick fracture, Bone pain, Bowing of legs, Enlarged skull (increased hat size), Cranial nerve compression, Radiculopathy at spine, Erythema over affected bone area due to hypervascularity.
What is a lab finding in Paget’s disease?
Increased bone alkaline phosphatase.
Paget’s disease leads to an increased risk for?
Osteosarcoma.
What are 2 treatments for Paget’s disease?
Calcitonin, Bisphosphonates.
Osteitis Fibrosa Cystica is a classic bone disease of?
Hyperparathyroidism.
Parathyroid adenoma leads to what 3 lab findings?
↑ PTH, Hypercalcemia, ↓ Phosphate.
What are 2 X-ray findings in Osteitis Fibrosa Cystica?
-Subperiosteal bone resorption: irregular or indented edges to bone
-Brown tumors: collection of giant osteoclasts in bone, appears as black spaces.
What is Renal Osteodystrophy? What does this include?
Bone abnormalities seen in renal failure: Osteitis Fibrosa Cystica, Rickets/osteomalacia, Osteopenia/osteoporosis, Growth retardation, Bone pain, Fractures.
What are 4 lab findings in Renal Osteodystrophy?
↓ Calcium, ↓ Vitamin D (active form), ↑ PTH, ↑ Phosphate.
What are 4 bone disorders that will have normal Ca2+ and PTH?
Osteoporosis, Osteopetrosis, Paget Disease, Bone Tumors.
Does Osteoporosis affect Trabecular or Cortical bone more?
Trabecular (high surface area).
What are 3 areas with high trabecular bone content?
Spine, Head of femur (hip), Wrist (distal radius).
Osteoporosis is common in what demographic?
Elderly white women.
When does peak bone mass occur?
Young adulthood.
Why are men less likely to have osteoporosis?
They achieve higher peak bone mass.
What is a standard recommendation to prevent Osteoporosis?
Weight bearing activity → ↑ bone mass.
What are Calcium, PTH, Alkaline phosphatase findings in Osteoporosis?
All normal.
What are Secondary Causes of Osteoporosis?
-Glucocorticoids: increase bone resorption, decrease bone formation
-Alcohol
-Smoking: accelerates bone loss
-Phenobarbital, Phenytoin, Carbamazepine
-Unfractionated Heparin (long term)
-Thyroid hormone Replacement: Too high dose → iatrogenic hyperthyroidism
-Hyperthyroidism
-Hyperparathyroidism
-Multiple myeloma
-Malabsorption syndromes (poor absorption of Ca2+/Vit D deficiency).
What is the underlying mechanism of Phenobarbital/Phenytoin causing Osteoporosis?
P450 enzymes inducer → Increases breakdown of vitamin D → Less calcium → increased PTH → bone loss.
What test should be performed for a patient on thyroid replacement therapy to minimize progression of bone loss?
TSH (if TSH is low then need to lower dose).
What are 2 ways to diagnose Osteoporosis?
-Fragility fracture
-T-score of 2.5 or lower on DXA.
What screening test is used for Osteoporosis? Who is this recommended for?
-Dual-energy X-ray absorptiometry (DXA) → T score
-Women >65 y/o.
How is a T score obtained in Dual-energy X-ray absorptiometry (DXA)?
Compare patient BMD vs. healthy 30 year old BMD (-1.0 or higher is normal).
What are 2 classic areas for fractures in a patient with Osteoporosis?
-Hip
-Spine: often occur slowly over time → loss of height, kyphosis.
What are 4 lifestyle modifications for Osteoporosis Therapy?
Smoking cessation, Avoid heavy alcohol use, Weight bearing exercise, Ca2+ and vitamin D supplementation.
What is the mechanism of Bisphosphonates?
Pyrophosphate analog → binds calcium, accumulate in bone → taken up by osteoclasts → inhibits osteoclasts.
What are adverse effects of Oral Bisphosphonates?
Upper GI upset: Reflux, esophagitis, esophageal ulcers.
How should Oral Bisphosphonates be taken? How often are they usually taken?
-Take with water on empty stomach
-Remain upright for 30 minutes
-Often taken weekly.
What are adverse effects of IV Bisphosphonates? This can be treated with?
Flu-like symptoms (low grade fever, myalgias) → ibuprofen, acetaminophen.
How often is IV Bisphosphonates administered?
3-months to annually (Long dosing intervals).
What are 2 uncommon Adverse effects of Bisphosphonates?
Atypical femur fractures, Osteonecrosis of the jaw (avascular necrosis).
What are Atypical femur fractures?
-Below less trochanter
-Diaphyseal
-No or minimal trauma.
What is Teriparatide? How is it used?
Recombinant human PTH, increases osteoblast bone formation
Low dose daily SQ injection.
What are 2 adverse effects of Teriparatide?
Brief rise in serum calcium, Theoretical risk of osteosarcoma.
What form of Calcitonin is used in humans?
Salmon calcitonin.
What is the mechanism of Denosumab?
Monoclonal RANK-L antibody → block osteoclast activation.
Which is more common: Bone metastasis or Primary bone tumor?
Bone metastasis.
Where in the bone are Bone metastasis most common?
Diaphysis.
What are the 2 types of Metastatic bone lesion? What cancer are they associated with?
Osteoclastic lesion: multiple myeloma, Osteoblastic lesion: Prostate carcinoma.
Primary Bone Tumors often occur in?
Children/young adults.
Primary Bone Tumors are more common in [M/W]?
Men.
Primary Bone Tumors usually involve what bones?
Long bones, especially at knees.
Primary Bone Tumors may cause what 2 symptoms?
Bone pain, Pathologic fractures (proximal femur and humerus are most frequent sites).
What is Osteoid Osteoma? Where do they commonly occur?
Benign small (<2cm) tumor of bone of young men (tumor of osteoblasts)
Occur in appendicular skeleton.
Is Osteoid Osteoma responsive to NSAIDs or aspirin?
Yes.
Osteoid Osteoma presents as?
Bone pain at night.
Where in the bone does Osteoid Osteoma occur? How does it appear histologically?
Surface of cortex of diaphysis
Osteoid core with rim of woven bone.
How does Osteoid Osteoma appear on X-ray?
Bump on the edge of the bone with central osteoid core.
Osteoblastoma often involves what bone?
Spine.
Is pain from Osteoblastoma responsive to NSAIDs or aspirin?
No.
What is the gene mutation in Gardner’s Syndrome?
APC gene mutation.
Gardner’s Syndrome is a variant of?
Familial Adenomatous Polyposis.
What bone manifestation often occurs in Gardner’s syndrome? Where do they usually occur?
Osteomas, usually in skull or mandible.
What is the most common primary bone tumor?
Osteosarcoma.
Osteosarcoma is a malignant bone tumor of?
Osteoblasts.
What is the age distribution of Osteosarcoma?
Bimodal: 75% young adults, 25% older adults (i.e. Paget’s).
Histopathology of Osteosarcoma?
Pleomorphic cells with irregular osteoid formation (pink).
What is the clinical presentation of Osteosarcoma? Where do they commonly occur?
Painful, enlarging mass on bone usually in metaphysis of long bones
50% occur at knee (distal femur, proximal tibia).