Metabolic Bone Diseases (Subscribe)

Categories

Mucolipidoses (5)
A group of inherited metabolic diseases characterized by the accumulation of excessive amounts of acid mucopolysaccharides, sphingolipids, and/or glycolipids in visceral and mesenchymal cells. Abnormal amounts of sphingolipids or glycolipids are present in neural tissue. Mental retardation and skeletal changes, most notably dysostosis multiplex, occur frequently.
MeSH Search Term "Mucolipidoses"[mesh]
ICD-10 Code E75 Disorders of sphingolipid metabolism and other lipid storage disorders
SNOMED-CT Term Mucolipidosis (disorder) Concept ID: 70528007
Osteomalacia (11)
A condition marked by softening of the bones (due to impaired mineralization, with excess accumulation of osteoid), with pain, tenderness, muscular weakness, anorexia, and loss of weight, resulting from deficiency of vitamin D and calcium. (Dorland, 27th ed)
MeSH Search Term "Osteomalacia"[mesh]
ICD-10 Code M83 Adult osteomalacia
SNOMED-CT term Osteomalacia (disorder) Concept ID: 4598005
Osteoporosis (47)
Reduction of bone mass without alteration in the composition of bone, leading to fractures. Primary osteoporosis can be of two major types: postmenopausal osteoporosis (OSTEOPOROSIS, POSTMENOPAUSAL) and age-related or senile osteoporosis.
MeSH Search Term "Osteoporosis"[mesh]
ICD-10 Code M81 Osteoporosis without pathological fracture
SNOMED-CT Term Osteoporosis (disorder) Concept ID: 64859006
Pagets (25)
Paget's Disease of Bone, Osteitis Deformans
MeSH Search Term "Osteitis, Deformans"[mesh] Paget's Disease of Bone is an entry term
ICD-10 Code M88 Paget's disease of bone [osteitis deformans]
SNOMED-CT term Osteitis deformans (disorder) Concept ID: 2089002
Synonyms - Osteitis deformans
Paget's disease of bone
Osteitis deformans (disorder)
Pathologic Bone Demineralization (9)
Decrease, loss, or removal of the mineral constituents of bones. Temporary loss of bone mineral content is especially associated with space flight, weightlessness, and extended immobilization. OSTEOPOROSIS is permanent, includes reduction of total bone mass, and is associated with increased rate of fractures. CALCIFICATION, PHYSIOLOGIC is the process of bone remineralizing.
MeSH Search Term "Bone Demineralization, Pathologic"[mesh]
OCD-10 Code M81.9 Osteoporosis, unspecified
SNOMED-CT Term Astronaut-bone demineralization syndrome (disorder) Concept ID: 129566001
Pseudohypoparathyroidism (7)
A hereditary condition clinically resembling HYPOPARATHYROIDISM, but caused by failure of response to rather than deficiency of parathyroid hormones. It is characterized by hypocalcemia and hyperphosphatemia, and is commonly associated with short stature, obesity, short metacarpals, and ectopic calcification.
MeSH Search Term "Pseudohypoparathyroidsim"[mesh]
MeSH Search Term ""[mesh]
ICD-10 Code E20.1 Pseudohypoparathyroidism
SNOMED-CT Term Pseudohypoparathyroidism (disorder) Concept ID: 58976002
Synonyms - stitutional chronic hypocalcemia
Familial pseudohypoparathyroidis
Parathyroid hormone resistant hypoparathyroidism
Albright hereditary osteodystrophy
Constitutional chronic hypocalcaemia
Pseudohypoparathyroidism (disorder)
Renal Osteodystrophy (8)
Decalcification of bone or abnormal bone development due to chronic KIDNEY DISEASES, in which 1,25-DIHYDROXYVITAMIN D3 synthesis by the kidneys is impaired, leading to reduced negative feedback on PARATHYROID HORMONE. The resulting SECONDARY HYPERPARATHYROIDISM eventually leads to bone disorders.
MeSH Search Term "Renal Osteodystrophy"[mesh]
ICD-10 Code N25.0 Renal osteodystrophy
SNOMED-CT Term Renal osteodystrophy (disorder) Concept ID: 16726004
Synonyms - Renal osteodystrophy
Renal rickets
Renal bone disease
ROD - Renal osteodystrophy
Renal osteodystrophy (disorder)
Rickets (19)
A condition caused by deficiency of VITAMIN D, especially in infancy and childhood, with disturbance of normal ossification. The disease is marked by bending and distortion of the bones under muscular action, by the formation of nodular enlargements on the ends and sides of the bones, by delayed closure of the fontanels, pain in the muscles, and sweating of the head. Vitamin D and sunlight together with an adequate diet are curative, provided that the parathyroid glands are functioning properly.
MeSH Search Term "Rickets"[mesh]
ICD-10 Code E55.0 Rickets, active
SNOMED-CT Term Rickets (disorder) Concept ID: 41345002

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Abnormalities associated with Vitamin D

Discussion: - primary function of 1,25 OH2D3) is to maintain skeletal homeostasis as well as for maintenance of plasma Ca homeostasis; - primary effect of lack of Vit D is decrease in miceralization of newly formed bone matrix (osteoid); - rate of bone formation is decreased; - net result is less total bone & marked change in quality of bone; - only minute amounts of vitamin D are necessary for parathyroid hormone to carry out its actions on bone and kidney; - osteomalacia, group of dz processes characterized by defective mineralizaiton can be caused by any problem resulting in inadequate amounts of Vit D or low plasma PO4; - in osteomalacia defective mineralizaiton results in relative increase in amount of osteoid (unmineralized bone matrix) in bone;

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Metabolic Bone Diseases

Sections on - Bone multicellular units Calcium supplements: Calcitonin Differential Dx Estrogen: HyperPTH / HypoPTH HypoCa / HyperCa Hypophosphatemic Vitamin D-resistant rickets Hyperthyroidism MSK Changes Associated w/ Steroids Osteomalacia Osteoporosis, Postmenopausal Pagets Disease Renal Disease: effects on bone Rickets Vit D & Abnormalities Wheeless' Textbook of Orthopaedics

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Bone multicellular units

- generalized pathologic processes in bone can be best understood by understanding how these processes alter the normal sequence of bone remodeling as described in the previous chapter; - bone remodeling occurs in local groups of osteoblasts and osteoclasts called bone multicellular units (BMU); - each unit is organized into "cutting cone" of osteoclasts reabsorbing bone followed by trail of osteoblasts reforming the bone to fill defect left by osteoclasts; - end product is a new osteon;

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Calcitonin

- contraindicated w/ clinical allergy, must periodically examine urine sediment with chronic use; - for symptomatic Paget's Disease of bone, hypercalcemia, post-menopausal osteoporosis (in addition to supplemental calcium, adequate vitamin D intake, and adequate diet);

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Calcium supplements

calcium content of various supplements: - 8 oz of milk: 250-300 mg (and also contains 100 international units of vitamin D); - 1 gm of calcium is present in 2.5 gm of calcium carbonate; - 1 gm of calcium is present in 5.0 gm of calcium citrate; - 1 gm of calcium is present in 8.0 gm of calcium lactate; - 1 gm of calcium is present in 10.0 gm of calcium gluconate; - phoslo - calcium acetate: 667 MG - calcium acetate anhydrous 667 MG = Calcium 169 M - calcium carbonate: - Os-Cal 250 = 625mg calcium carbonate (each tab contains 250mg of elemental calcium and 125 USP units of Vit D); - Os-Cal 500 = 1250 mg calcium carbonate (each tab contains 500mg of elemental calcium); - Os-Cal Forte = 250mg elemental calcium plus vitamins and minerals; - CaCO3 650mg PO tid/qid is good for slowing diarrhea induced by tube feeding; - for calcium replacment: Adults: 500mg PO qd or 1 tab tid; - cal-bid: calcium supplement w/ Vit C and D added - 625 mmg (= 250 mmg elemental calcium);

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HyperCalcemia

Wheeless' Textbook of Orthopaedics Discussion: - physical properties - state in body fluids - calcium is a necessary & important addition to cell membranes, giving strength to these structures and regulating permeability; - physiologic roles of calcium are well established; - abnormally low concentrations of Ca permit spontaneous discharges of both sensory & motor fibers in peripheral nerves, leading to tetany; - see depolarization and calcium regulation of muscle contraction; - w/ elevated levels, nerve impulses are blocked, leading to coma; - normal levels: - serum: 4.2-5.3 mEq/L or 8.5-10.5 mg/dL; - ionized: 2.24-2.46 mEq/L or 4.48-4.92 mg/dL

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Hyperparathyroidism

Wheeless' Textbook of Orthopaedics Discussion: - a disorder which is caused by excessive production of parathyroid hormone which leads to hypercalcemia, recurrent nephrolithiasis, pancreatitis, peptic ulcers, and mental changes; - incidence of approx 5 /10,000 pts per year; - usually affects adults over 50 yrs & occurs more commonly in females; - causes: - in most cases is due to single parathyroid adenoma (80% of patients); - malignant tumor: occurs in about 1% of patients with hyperparathyroidism; - occurs often in association w/ multiple endocrine neoplasia syndrome, and rarely to parathyroid carcinoma; - hyperparathyoidism is sometimes seen in renal cell carcinoma and squamous cell carcinoma

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Hyperviaminosis POSNA Study Guide

Hypervitaminosis Objectives 1. List the two vitamins most often associated with hypervitaminosis in children 2. Describe the major lifethreatening effects of these hypervitaminoses

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hypervitaminosis A CHORUS

* acute
o ingestion of>1,000,000 IU --> increased intracranial pressure
* chronic
o 1-3 years
o pruritis
o hard, tender masses in extremities
o long latency between intake and sxs
xray findings:
* periostitis in diaphyses of ulnae and metatarsals
* symmetric
* can cause premature fusion of ossification centers

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Hypoparathyroidism

Wheeless' Textbook of Orthopaedics Discussion: - most common cause of hypoparathyroidism is inadvertant damage or removal of the parathyroids during surgical removal of the thyroid; - in idiopathic cases, look for ectodermal changes, mental retardation, monilial infections, low Ca; - congenital hypoparathyroid & late onset hypoparathyroidism from other causes in adulthood are rare conditions; - pseudohypoparathyroidism is another cause of this disorder; - end organ unresponsiveness to parathyroid hormone; - patients tend to be short and may have short metacarpals (index, ring, little);

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Management of HypoCalcemia

Wheeless' Textbook of Orthopaedics Discussion: - physical properties - state in body fluids - physiologic roles of calcium are well established; - abnormally low concentrations of Ca permit spontaneous discharges of both sensory & motor fibers in peripheral nerves, leading to tetany; - w/ elevated levels, nerve impulses are blocked, leading to coma; - calcium is also necessary & important addition to cell membranes, giving strength to these structures and regulating permeability; - sudden death may occur when the ionized calcium falls below 2 mg/dL;

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Osteoprotegerin and its Ligand: A New Paradigm for Regulation of Osteoclastogenesis and Bone Resorption

In just 3 years, striking new advances have been made in understanding the molecular mechanisms that govern the crosstalk between osteoblasts/stromal cells and hemopoietic osteoclast precursor cells that leads to osteoclastogenesis. Led first by the discovery of osteoprotegerin (OPG), a naturally occurring protein with potent osteoclastogenesis inhibitory activity, rapid progress was made to the isolation of RANKL, a transmembrane ligand expressed on osteoblasts/stromal cells, that binds to RANK, a transmembrane receptor on hemopoietic osteoclast precursor cells. The interaction of RANK and RANKL initiates a signaling and gene expression cascade that results in differentiation and maturation of osteoclast precursor cells to active osteoclasts capable of resorbing bone. Osteoprotegerin acts as a decoy receptor; it binds to RANKL and blocks its interaction with RANK, thus inhibiting osteoclast development. Many of the calciotropic hormones and cytokines, including vitamin D3, parathyroid hormone, prostaglandin E2 and interleukin-11, appear to stimulate osteoclastogenesis through the dual action of inhibiting production of OPG and stimulating production of RANKL. Estrogen, on the other hand, appears to inhibit production of RANKL and RANKL-stimulated osteoclastogenesis. Recently, the results of the first clinical trial with OPG supported its potential as a therapeutic agent for osteoporosis. The new understanding provided by the RANK/RANKL/OPG paradigm for both differentiation and activation of osteoclasts has had tremendous impact on the field of bone biology and has opened new avenues for development of possible treatments of diseases characterized by excessive bone resorption. from Medscape General Medicineā„¢ Posted 03/08/2000

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Scurvy POSNA Study Guide

Objectives
1. Describe the pathophysiology of scurvy
2. Describe presenting clinical symptoms and radiographic features of scurvy

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Vit D Discussion Wheeless

primary function of vitamin D is to maintain skeletal calcium homeostasis;
- promotes gut absorption of calcium (and absorption of phosphorous);
- promotes bone absorption;
- important for maintaining adequate quantities of Ca & Phos for bone formation thru its effects on the kidney & gut;
- in addition, it may have a direct effect on bone formation;
- proper functioning of the vitamin D system is necessary for PTH to maintain plasma calcium effectively, although drops in the plasma Ca occur only with severe Vit D depletion;
- it appears that only minute amounts of Vit D are necessary for PTH to carry out its actions on the bone and kidney
Wheeless' Textbook of Orthopaedics

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