WordNet

remove the bones from; "bone the turkey before roasting it" (同)debone
the porous calcified substance from which bones are made (同)osseous_tissue
consisting of or made up of bone; "a bony substance"; "the bony framework of the body"
a shade of white the color of bleached bones (同)ivory, pearl, off-white
rigid connective tissue that makes up the skeleton of vertebrates (同)os
relating to minerals; "mineral elements"; "mineral deposits"
solid homogeneous inorganic substances occurring in nature having a definite chemical composition
composed of matter other than plant or animal; "the inorganic mineral world"
having bones as specified; "his lanky long-boned body"
having had the bones removed; "a boneless rib roast"; "a boned (or deboned) fish" (同)deboned
a percussion instrument consisting of a pair of hollow pieces of wood or bone (usually held between the thumb and fingers) that are made to click together (as by Spanish dancers) in rhythm with the dance (同)castanets, clappers, finger cymbals
the amount per unit size (同)denseness

PrepTutorEJDIC

〈C〉骨 / 〈U〉骨を作っている物質,骨質 / 《複数形で》骨格;死骸(がい) / 〈魚など〉‘の'骨を取る
(動植物に対して)『無機物』 / 『鉱物』,鉱石 / 《複数形で》《英》炭酸水,清涼飲料(mineral water) / 鉱物の,鉱物質を含む
(魚など)骨を取り除いた / (衣服が)(コルセットなどで)骨で張りをつけた[ような]
〈U〉『密集』;『密度』,濃さ / 〈U〉〈C〉(物質の)密度,濃度,比重 / 〈U〉《話》頭の鈍さ,愚鈍さ

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/18 14:11:27」(JST)

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A scanner used to measure bone density with dual energy X-ray absorptiometry.

Bone density (or bone mineral density) is a medical term normally referring to the amount of mineral matter per square centimeter of bones.^[1] Bone density (or BMD) is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk.

This medical bone density is not the true physical "density" of the bone, which would be computed as mass per volume. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. The measurement is painless and non-invasive and involves low radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip.^[2] The forearm may be scanned if the hip and lumbar spine are not accessible.

There is a statistical association between poor bone density and higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to much medical cost, inability to live independently, and even risk of death. Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.

Testing

Bone density tests are not necessary for people without risk factors for weak bones.^[3]^[4] Unnecessary testing is more likely to result in superfluous treatment rather than discovery of a true problem.^[4]

Indications for testing

The following are risk factors for low bone density and primary considerations for the need for a bone density test.

females age 65^[4]
males age 70^[4]
people over age 50 with any of the following:
- previous bone fracture from minor trauma^[4]
- rheumatoid arthritis^[4]
- low body weight^[4]
- a parent with a hip fracture^[4]
Individuals with vertebral abnormalities.^[5]
Individuals receiving, or planning to receive, long-term glucocorticoid (steroid) therapy.^[5]
Individuals with primary hyperparathyroidism.^[5]
Individuals being monitored to assess the response or efficacy of an approved osteoporosis drug therapy.^[5]
Individuals with a history of eating disorders^[5]

Other considerations which related to risk of low bone density and the need for a test include smoking habits, drinking habits, the long-term use of corticosteroid drugs, and a vitamin D deficiency.^[4]

Overtesting and treatment

For those people who do have bone density tests, two conditions which may be detected are osteoporosis and osteopenia.^[4] The usual response to either of these indications is consultation with a physician.^[4]

Terms

Results are often reported in 3 terms:

Measured areal density in g cm⁻²
z-score, the number of standard deviations above or below the mean for the patient's age, sex and ethnicity
t-score, the number of standard deviations above or below the mean for a healthy 30 year old adult of the same sex and ethnicity as the patient

Types of tests

Illustration of Bone Densitometry Scan

While there are many different types of BMD tests, all are non-invasive. Most tests differ in which bones are measured to determine the BMD result.

These tests include:

Dual-energy X-ray absorptiometry (DXA or DEXA)
Quantitative computed tomography (QCT)
Qualitative ultrasound (QUS)
Single photon absorptiometry (SPA)
Dual photon absorptiometry (DPA)
Digital X-ray radiogrammetry (DXR)
Single energy X-ray absorptiometry (SEXA)

DEXA is currently the most widely used, but ultrasound has been described as a more cost-effective approach to measure bone density.^[6]

The test works by measuring a specific bone or bones, usually the spine, hip, and wrist. The density of these bones is then compared with an average index based on age, sex, and size. The resulting comparison is used to determine risk for fractures and the stage of osteoporosis in an individual.

Average bone mineral density = BMC / W [g/cm²]

BMC = bone mineral content = g/cm
W = width at the scanned line

Interpretation

Results are generally scored by two measures, the T-score and the Z-score. Scores indicate the amount one's bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.

T-score

The T-score is the relevant measure when screening for osteoporosis. It is the bone mineral density (BMD) at the site when compared to the young normal reference mean. It is a comparison of a patient's BMD to that of a healthy thirty-year-old. The US standard is to use data for a thirty-year-old of the same sex and ethnicity, but the WHO recommends using data for a thirty-year-old white female for everyone.^[7] Values for thirty-year-olds are used in post-menopausal women and men over age 50 because they better predict risk of future fracture.^[8] The criteria of the World Health Organization are:^[9]

Normal is a T-score of −1.0 or higher
Osteopenia is defined as between −1.0 and −2.5
Osteoporosis is defined as −2.5 or lower, meaning a bone density that is two and a half standard deviations below the mean of a thirty-year-old man/woman.

Hip fractures per 1000 patient-years^[10]
WHO category	Age 50–64	Age > 64	Overall
Normal	5.3	9.4	6.6
Osteopenia	11.4	19.6	15.7
Osteoporosis	22.4	46.6	40.6

Z-score

The Z-score is the comparison to the age-matched normal and is usually used in cases of severe osteoporosis. This is the number of standard deviations a patient's BMD differs from the average BMD of their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of 50, and in children.^[8] It is most useful when the score is less than 2 standard deviations below this normal. In this setting, it is helpful to scrutinize for coexisting illnesses that may contribute to osteoporosis such as glucocorticoid therapy, hyperparathyroidism, or alcoholism.

Limitations

Use of BMD has several limitations.

Measurement can be affected by the size of the patient, the thickness of tissue overlying the bone, and other factors extraneous to the bones.
Bone density is a proxy measurement for bone strength, which is the resistance to fracture and the truly significant characteristic. Although the two are usually related, there are some circumstances in which bone density is a poorer indicator of bone strength.
Reference standards for some populations (e.g., children) are unavailable for many of the methods used.
Crushed vertebrae can result in falsely high bone density so must be excluded from analysis.

Diet

There may be associations between some forms of BMD and diet.^{[citation needed]}

References

^ Bone Density at the US National Library of Medicine Medical Subject Headings (MeSH)
^ Cole RE (June 2008). "Improving clinical decisions for women at risk of osteoporosis: dual-femur bone mineral density testing". J Am Osteopath Assoc 108 (6): 289–95. PMID 18587077.
^ American Academy of Family Physicians, presented by ABIM Foundation, "Five Things Physicians and Patients Should Question" (PDF), Choosing Wisely: an initiative of the ABIM Foundation (American Academy of Family Physicians), retrieved August 14, 2012
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Consumer Reports; American Academy of Family Physicians (May 2012), "Bone-density tests: When you need them — and when you don't" (PDF), Choosing Wisely: an initiative of the ABIM Foundation (Consumer Reports), retrieved August 14, 2012
^ ^a ^b ^c ^d ^e "NOF - Bone Mass Measurement". Archived from the original on 2008-03-07. Retrieved 2008-03-20.
^ "Bone densitometry". Retrieved 2008-09-02.
^ Unknown, Unknown (2011-07-29). "T and Z scores.". University of Washington Bone Physics. Retrieved 2013-06-22.
^ ^a ^b Richmond, Bradford (2007-11-13). "Osteoporosis and bone mineral density.". American College of Radiology. Retrieved 2008-05-11.
^ WHO Scientific Group on the Prevention and Management of Osteoporosis (2000 : Geneva, Switzerland) (2003). "Prevention and management of osteoporosis : report of a WHO scientific group" (pdf). Retrieved 2007-05-31.
^ Cranney A, Jamal SA, Tsang JF, Josse RG, Leslie WD (2007). "Low bone mineral density and fracture burden in postmenopausal women". Canadian Medical Association Journal 177 (6): 575–80. doi:10.1503/cmaj.070234. PMC 1963365. PMID 17846439.

UpToDate Contents

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1. 骨粗鬆症のスクリーニング screening for osteoporosis
2. 閉経後の女性における骨粗鬆症のマネージメントの概要 overview of the management of osteoporosis in postmenopausal women
3. ニ重エネルギーX線吸収測定の概要 overview of dual energy x ray absorptiometry
4. 骨粗鬆症性骨折のリスク評価 osteoporotic fracture risk assessment
5. ストレス骨折の概要 overview of stress fractures

English Journal

Assessment of lean (muscle) mass and its distribution by dual energy X-ray absorptiometry in healthy Indian females.

Marwaha RK1, Garg MK, Bhadra K, Mithal A, Tandon N.
Archives of osteoporosis.Arch Osteoporos.2014 Dec;9(1):186. doi: 10.1007/s11657-014-0186-z. Epub 2014 Jul 1.
Mean appendicular lean mass increased from the second decade to reach maximum in the fourth decade in Indian women. Post-menopausal females with LMM were significantly older, leaner, and had lower bone mineral density (BMD). Lean mass and ASMI were negatively correlated with age and positively with
PMID 24981868

The Tromsø Study: Fit Futures: a study of Norwegian adolescents' lifestyle and bone health.

Winther A1, Dennison E, Ahmed LA, Furberg AS, Grimnes G, Jorde R, Gjesdal CG, Emaus N.
Archives of osteoporosis.Arch Osteoporos.2014 Dec;9(1):185. doi: 10.1007/s11657-014-0185-0. Epub 2014 Jun 4.
Bone mass achievement predicts later fracture risk. This population-based study describes bone mineral density (BMD) levels and associated factors in Norwegian adolescents. Compared with international reference ranges, BMD levels appear higher and physical activity levels are positively associated w
PMID 24893722

Bone microarchitecture and strength of the radius and tibia in a reference population of young adults: an HR-pQCT study.

Burt LA1, Macdonald HM, Hanley DA, Boyd SK.
Archives of osteoporosis.Arch Osteoporos.2014 Dec;9(1):183. doi: 10.1007/s11657-014-0183-2. Epub 2014 May 27.
Within a normative youth cohort (16-29 years) bone parameters for males and females remained stable at the radius. At the tibia, a peak was observed for females at 16-19 years, with bone density and strength decreasing by 29 years.PURPOSE: To determine if bone microstructural and strength parameters
PMID 24862979

Japanese Journal

The Estimation of Proximal Femoral Bone Mineral Density of Young Women on "Diagnostic Criteria for Primary Osteoporosis: Year 2000 Revision"

HAYASHIDA Keiichi,TAKEDA Yoshihiro,YAMAMOTO Kenyu,SUESADA Yasuhide,AZUMA Masami
大阪教育大学紀要　第Ⅲ部門　自然科学・応用科学 61(2), 55-60, 2013-02-28
… The validity of"Diagnostic criteria for osteoporosis: year 2000 revision"（the 2000 year criteria）was studied on the estimation of proximal femoral bone mineral density（BMD）, especially on the age range of young adult mean（YAM）in the 2000 year criteria and on the compatibility of dual energy X-ray absorptiometry（DXA）equipments used for the measurement of proximal femoral BMD. …
NAID 120005255540

Genistein affects osteoblastic MC3T3-E1 cells both through estrogen receptor and BMP-Smad signaling pathways

Hinenoya Hajime,Katsuyama Hironobu,Nohno Tsutomu
川崎医学会誌 39(1), 21-31, 2013-00-00
… Many epidemiological studies show that genistein intake is effective for maintaining bone mineral density (BMD). … Because the reason for the efficacy of genistein as a bone protective agent in vivo remains unclear, we investigated the mechanisms underlying the effects of genistein on BMD in relation to BMP-Smad signaling systems. …
NAID 110009559339

〔研究ノート〕慢性腎臓病モデルラットの骨密度維持に対する食餌アルギニンあるいは大豆イソフラボン抽出物投与の有効性評価に関する基礎的研究

間野琴子,宮内智美,春宮覚 [他],海老沢秀道
學苑 866, 47-55, 2012-12-01
… The present study was carried out to determine whether dietary isoflavone and arginine could preserve the renal function and prevent renal injury and bone mineral density loss in the chronic kidney disease model rat. …
NAID 110009491056