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abnormal softening of bones caused by deficiencies of phosphorus or calcium or vitamin D

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/24 16:45:22」(JST)

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Osteomalacia is the softening of the bones caused by defective bone mineralization secondary to inadequate levels of available phosphate and calcium, or because of overactive resorption of calcium from the bone which can be caused by hyperparathyroidism (which causes hypercalcemia).^[1] Osteomalacia in children is known as rickets, and because of this, use of the term "osteomalacia" is often restricted to the milder, adult form of the disease. Signs and symptoms can include diffuse body pains, muscle weakness, and fragility of the bones.

The most common cause of osteomalacia is a deficiency of vitamin D, which is normally derived from sunlight exposure and, to a lesser extent, from the diet.^[2] The most specific screening test for vitamin D deficiency in otherwise healthy individuals is a serum 25(OH)D level.^[3] Less common causes of osteomalacia can include hereditary deficiencies of vitamin D or phosphate (which would typically be identified in childhood) or malignancy.

Measures to prevent and treat osteomalacia usually revolve around intake of vitamin D and calcium supplements. Vitamin D should always be administered in conjunction with calcium supplementation since most of the consequences of vitamin D deficiency are a result of impaired mineral ion homeostasis.^[4]

Nursing home residents and the homebound elderly population are at particular risk for vitamin D deficiency, as these populations typically receive little sun exposure. In addition, both the efficiency of vitamin D synthesis in the skin and the absorption of vitamin D from the intestine decline with age, thus further increasing the risk in these populations. Other groups at risk include individuals with malabsorption secondary to gastrointestinal bypass surgery or celiac disease, and individuals who immigrate from warm climates to cold climates, especially women who wear traditional veils or dresses that prevent sun exposure.^[5]

General characteristics

Osteomalacia is a generalized bone condition in which there is inadequate mineralization of the bone. Many of the effects of the disease overlap with the more common osteoporosis, but the two diseases are significantly different. There are two main causes of osteomalacia: (1) insufficient calcium absorption from the intestine because of lack of dietary calcium or a deficiency of, or resistance to, the action of vitamin D; and (2) phosphate deficiency caused by increased renal losses.

Osteomalacia is derived from Greek: osteo- which means "bone", and malacia which means "softness". In the past, the disease was also known as malacosteon and its Latin-derived equivalent, mollities ossium. Osteomalacia is associated with increase in osteoid maturation time.

Causes

The causes of adult osteomalacia are varied, but ultimately result in a vitamin D deficiency:

Insufficient nutritional quantities or faulty metabolism of vitamin D or phosphorus
Renal tubular acidosis
Malnutrition during pregnancy
Malabsorption syndrome
Hypophosphatemia^[6]
Chronic kidney failure
Tumor-induced osteomalacia
Long-term anticonvulsant therapy^[7]
Celiac disease^[8]
Cadmium poisoning, Itai-itai disease

Signs and Symptoms

Diffuse joint and bone pain (especially of spine, pelvis, and legs)
Muscle weakness
Difficulty walking, often with waddling gait
Hypocalcemia (positive Chvostek sign)
Compressed vertebrae and diminished stature
Pelvic flattening
Weak, soft bones
Easy fracturing
Bending of bones

Clinical features

Osteomalacia in adults starts insidiously as aches and pains in the lumbar (lower back) region and thighs before spreading to the arms and ribs. The pain is symmetrical, non-radiating and accompanied by sensitivity in the involved bones. Proximal muscles are weak, and there is difficulty in climbing up stairs and getting up from a squatting position.

As a result of demineralization, the bones become less rigid. Physical signs include deformities like triradiate pelvis^[9] and lordosis. The patient has a typical "waddling" gait. However, these physical signs may derive from a previous osteomalacial state, since bones do not regain their original shape after they become deformed.

Pathologic fractures due to weight bearing may develop. Most of the time, the only alleged symptom is chronic fatigue, while bone aches are not spontaneous but only revealed by pressure or shocks.

It differs from renal osteodystrophy, where the latter shows hyperphosphatemia.

Biochemical findings

Biochemical features are similar to those of rickets. The major factor is an abnormally low vitamin D concentration in blood serum.

Major typical biochemical findings include:^[10]

Low serum and urinary calcium
Low serum phosphate, except in cases of renal osteodystrophy
Elevated serum alkaline phosphatase (due to an increase in compensatory osteoblast activity)
Elevated parathyroid hormone (due to low calcium)

Furthermore, a technetium bone scan will show increased activity (also due to increased osteoblasts).

Comparison of bone pathology
view talk edit Condition	Calcium	Phosphate	Alkaline phosphatase	Parathyroid hormone	Comments
Osteopenia	unaffected	unaffected	normal	unaffected	decreased bone mass
Osteopetrosis	unaffected	unaffected	elevated	unaffected^{[citation needed]}	thick dense bones also known as marble bone
Osteomalacia and rickets	decreased	decreased	elevated	elevated	soft bones
Osteitis fibrosa cystica	elevated	decreased	elevated	elevated	brown tumors
Paget's disease of bone	unaffected	unaffected	variable (depending on stage of disease)	unaffected	abnormal bone architecture

Radiographic characteristics

Radiological appearances include:

Pseudofractures, also called Looser's zones.
Protrusio acetabuli, a hip joint disorder

Treatment

Nutritional osteomalacia responds well to administration of 10,000 IU weekly of vitamin D for four to six weeks. Osteomalacia due to malabsorption may require treatment by injection or daily oral dosing^[11] of significant amounts of vitamin D.

References

^ TheFreeDictionary > osteomalacia Citing: Mosby's Medical Dictionary, 8th edition. Copyright 2009
^ MedlinePlus Medical Encyclopedia: Osteomalacia
^ Longo, Dan L. et al. (2012). Harrison's principles of internal medicine. (18th ed. ed.). New York: McGraw-Hill. ISBN 978-0-07174889-6.
^ Longo, Dan L. et al. (2012). Harrison's principles of internal medicine. (18th ed. ed.). New York: McGraw-Hill. ISBN 978-0-07174889-6.
^ Kennel, KA; Drake, MT; Hurley, DL (August 2010). "Vitamin D deficiency in adults: when to test and how to treat.". Mayo Clinic proceedings 85 (8): 752–7; quiz 757–8. PMID 20675513.
^ "Autoimmunity research foundation, Science behind Vitamin D". Retrieved 2011-07-19.
^ Pack, Alison (2008). "Bone health in people with epilepsy: is it impaired and what are the risk factors". Seizure 17 (2): 181–6. doi:10.1016/j.seizure.2007.11.020. PMID 18187347.
^ Albany, Costantine; Servetnyk, Zhanna (2009). "Disabling osteomalacia and myopathy as the only presenting features of celiac disease: a case report". Cases Journal 2 (1): 20. doi:10.1186/1757-1626-2-20. PMC 2626577. PMID 19128487.
^ Chakravorty, N. K. (1980). "Triradiate deformity of the pelvis in Paget's disease of bone.". Postgraduate Medical Journal 56 (653): 213–5. doi:10.1136/pgmj.56.653.213. PMC 2425842. PMID 7393817.
^ Holick, Michael F. (19 July 2007). "Vitamin D Deficiency". New England Journal of Medicine 357 (3): 266–281. doi:10.1056/NEJMra070553.
^ Eisman, John A. (1988). "6 Osteomalacia". Baillière's Clinical Endocrinology and Metabolism 2: 125–55. doi:10.1016/S0950-351X(88)80011-9.

UpToDate Contents

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1. 骨軟化症の臨床症状、診断、および治療 clinical manifestations diagnosis and treatment of osteomalacia
2. 骨軟化症の疫学および病因 epidemiology and etiology of osteomalacia
3. 遺伝性低リン血症性くる病と腫瘍誘発性骨軟化症 hereditary hypophosphatemic rickets and tumor induced osteomalacia
4. 小児におけるくる病の概要 overview of rickets in children
5. 成人におけるビタミンD欠乏症：定義、臨床症状、および治療 vitamin d deficiency in adults definition clinical manifestations and treatment

English Journal

Bilateral femoral neck insufficiency fractures secondary to vitamin D deficiency and concurrent corticosteroid use-a case report.

Carter T1, Nutt J, Simons A.Author information 1Department of Orthogeriatrics, Birmingham Heartlands Hospital, Birmingham, UK, tjcarter@doctors.org.uk.AbstractWe present a rare case of a 67-year-old Indian female who was found to have bilateral insufficiency of the neck of femur fractures secondary to osteomalacia from vitamin D deficiency, with her symptoms exacerbated by a course of oral steroids prescribed for suspected polymyalgia rheumatica.
Archives of osteoporosis.Arch Osteoporos.2014 Dec;9(1):172. doi: 10.1007/s11657-014-0172-5. Epub 2014 Feb 11.
We present a rare case of a 67-year-old Indian female who was found to have bilateral insufficiency of the neck of femur fractures secondary to osteomalacia from vitamin D deficiency, with her symptoms exacerbated by a course of oral steroids prescribed for suspected polymyalgia rheumatica.INTRODUCT
PMID 24515953

Severe hypocalcemia after denosumab in a patient with acquired Fanconi syndrome.

Shafqat H1, Alquadan KF, Olszewski AJ.Author information 1Memorial Hospital of Rhode Island, 111 Brewster St., Pawtucket, RI, 02860, USA.AbstractWe report the case of a 48-year-old man with acquired Fanconi syndrome due to IgG-kappa monoclonal gammopathy, who received a single dose of denosumab 60 mg for secondary prevention of skeletal fractures, in conjunction with oral calcium and vitamin D supplementation. The treatment was complicated with a severe, symptomatic hypocalcemia occurring 1 month after the injection and necessitating 4 weeks of intravenous calcium gluconate therapy. Similarly to bisphosphonates, inhibitors of the receptor activator of nuclear factor kappa-B ligand may not be appropriate for the treatment of acquired Fanconi syndrome and other forms of osteomalacia regardless of the degree of renal insufficiency and vitamin D levels. Clinicians should carefully interpret the radiographic and bone densitometry results in light of diverse mechanisms of bone demineralization and potential dependence of calcium homeostasis on high bone turnover.
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA.Osteoporos Int.2014 Mar;25(3):1187-90. doi: 10.1007/s00198-013-2533-0. Epub 2013 Oct 25.
We report the case of a 48-year-old man with acquired Fanconi syndrome due to IgG-kappa monoclonal gammopathy, who received a single dose of denosumab 60 mg for secondary prevention of skeletal fractures, in conjunction with oral calcium and vitamin D supplementation. The treatment was complicated
PMID 24158473

Hypophosphatemic rickets due to perturbations in renal tubular function.

Penido MG1, Alon US.Author information 1Pediatric Nephrology Unit, Clinics Hospital, School of Medicine, Federal University of Minas Gerais, Av. Professor Alfredo Balena, 190, CEP, 30130100, Belo Horizonte, MG, Brazil, mariagorettipenido@gmail.com.AbstractThe common denominator for all types of rickets is hypophosphatemia, leading to inadequate supply of the mineral to the growing bone. Hypophosphatemia can result from insufficient uptake of the mineral from the gut or its disproportionate losses in the kidney, the latter being caused by either tubular abnormalities per se or the effect on the tubule of circulating factors like fibroblast growth factor-23 and parathyroid hormone (PTH). High serum levels of the latter result in most cases from abnormalities in vitamin D metabolism which lead to decreased calcium absorption in the gut and hypocalcemia, triggering PTH secretion. Rickets is a disorder of the growth plate and hence pediatric by definition. However, it is important to recognize that the effect of hypophosphatemia on other parts of the skeleton results in osteomalacia in both children and adults. This review addresses the etiology, pathophysiologic mechanisms, clinical manifestations and treatment of entities associated with hypophosphatemic rickets due to perturbations in renal tubular function.
Pediatric nephrology (Berlin, Germany).Pediatr Nephrol.2014 Mar;29(3):361-73. doi: 10.1007/s00467-013-2466-z. Epub 2013 May 1.
The common denominator for all types of rickets is hypophosphatemia, leading to inadequate supply of the mineral to the growing bone. Hypophosphatemia can result from insufficient uptake of the mineral from the gut or its disproportionate losses in the kidney, the latter being caused by either tubul
PMID 23636577

Japanese Journal

代謝性骨・関節疾患 (特集高齢者の骨・関節疾患 : 転倒予防に向けての取り組み) -- (高齢者の主な骨・関節疾患の病態・診断・治療)

遠藤逸朗
日本臨床 72(10), 1785-1791, 2014-10
NAID 40020213631

今月の症例抗B型肝炎ウイルス薬のアデフォビルにより薬剤性Fanconi症候群および低P血症性骨軟化症をきたした1例

廣瀬和俊,乳原善文,平松里佳子 [他]
日本内科学会雑誌 103(6), 1388-1390, 2014-06-10
NAID 40020123532

症例報告アデホビル長期投与中にFanconi症候群による低リン血性骨軟化症を発症したB型慢性肝炎の1例

石川和真,宮西浩嗣,保木寿文 [他]
肝臓 55(3), 162-169, 2014-03
NAID 40020025392

Related Pictures

★リンクテーブル★

リンク元

「骨軟化症」

Osteomalacia (rickets)
Classification and external resources
ICD-10	M83
ICD-9	268.2
DiseasesDB	9351
MedlinePlus	000376
eMedicine	ped/2014 radio/610
Patient UK	Osteomalacia
MeSH	D010018

　　[★]

英: osteomalacia
関: (小児のでは)くる病、骨粗鬆症

骨基質へのカルシウム沈着が障害され、類骨が多く生じる病態。
原因：ビタミンDの作用低下、リンの欠乏。　←　甲状腺機能低下症のように低カルシウム血症、高リン血症では本症が生じるのではなく、異所性石灰化がみられるらしい

[1] TheFreeDictionary > osteomalacia Citing: Mosby's Medical Dictionary, 8th edition. Copyright 2009

[2] MedlinePlus Medical Encyclopedia: Osteomalacia

[3] Longo, Dan L. et al. (2012). Harrison's principles of internal medicine. (18th ed. ed.). New York: McGraw-Hill. ISBN 978-0-07174889-6.

[4] Longo, Dan L. et al. (2012). Harrison's principles of internal medicine. (18th ed. ed.). New York: McGraw-Hill. ISBN 978-0-07174889-6.

[5] Kennel, KA; Drake, MT; Hurley, DL (August 2010). "Vitamin D deficiency in adults: when to test and how to treat.". Mayo Clinic proceedings 85 (8): 752–7; quiz 757–8. PMID 20675513.

[6] "Autoimmunity research foundation, Science behind Vitamin D". Retrieved 2011-07-19.

[7] Pack, Alison (2008). "Bone health in people with epilepsy: is it impaired and what are the risk factors". Seizure 17 (2): 181–6. doi:10.1016/j.seizure.2007.11.020. PMID 18187347.

[8] Albany, Costantine; Servetnyk, Zhanna (2009). "Disabling osteomalacia and myopathy as the only presenting features of celiac disease: a case report". Cases Journal 2 (1): 20. doi:10.1186/1757-1626-2-20. PMC 2626577. PMID 19128487.

[9] Chakravorty, N. K. (1980). "Triradiate deformity of the pelvis in Paget's disease of bone.". Postgraduate Medical Journal 56 (653): 213–5. doi:10.1136/pgmj.56.653.213. PMC 2425842. PMID 7393817.

[10] Holick, Michael F. (19 July 2007). "Vitamin D Deficiency". New England Journal of Medicine 357 (3): 266–281. doi:10.1056/NEJMra070553.

[11] Eisman, John A. (1988). "6 Osteomalacia". Baillière's Clinical Endocrinology and Metabolism 2: 125–55. doi:10.1016/S0950-351X(88)80011-9.

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osteomalacia