View source for Osteoporosis classification

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{{Osteoporosis}}
{{CMG}}; {{AE}}{{EG}}

== Overview ==
Osteoporosis is classified based on [[etiology]] and severity of the [[disease]]. Osteoporosis may be divided into primary and secondary types, based on [[disease]] [[etiology]]. On the basis of [[disease]] severity, it can be classified as [[osteopenia]], osteoporosis, and severe osteoporosis. Osteoporosis is rare in children and adolescents. Secondary osteoporosis results from various [[comorbidities]] or the use of certain [[medications]], whereas, [[idiopathic]] osteoporosis has no known cause.

==Classification==
[[Osteoporosis]] may be classified based on [[etiology]] and severity of the disease.<ref name="osteoporosis" /><ref name="pmid11341335" /><ref name="BachrachGordon2016" />
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{{Family tree | | | | | | | | | | | | | | | | A01 | | | | | | | | | | | | |A01= '''[[Osteoporosis]]'''}}
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{{Family tree | | | | | | | | | C01 | | | | | | | | | | | | | C02 | | | | | |C01= Based on<br>'''Severity'''| C02= Based on <br>'''Etiology'''}}
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{{Family tree | | | | C01 | | | | | | | | C02 | | | | | | | | C03 | | | | |C01= Children| C02= Adults|C03= Children, Adolescents, and Adults}}
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{{Family tree | | | | C01 | | | | | | | | C02 | | | | | | | | C03 | | | | |C01= '''Z-score measurement'''| C02= '''T-score measurement'''| C03= [[Bone loss]] due to other diseases?}}
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{{family tree | | E01 | | E02 | | E03 | | E04 | | E05 | | E06 | | E07 | | |E01= Z-score > -2.0 <br> without [[fracture]] history|E02= Z-score < -2.0 and significant [[fracture]] history<br> (2 or more long [[bone fractures]] before 10 years of age <br>or<br> 3 or more long [[bone fractures]] before 19 years of age)<br> '''''OR'''''<br> One or more [[vertebral fractures]] occurring in the absence of local disease or high-energy trauma|E03=-1 > T-score > -2.5|E04= T-score ≤ -2.5|E05=T-score ≤ -2.5 <br>'''''plus'''''<br> history of [[fracture]]|E06=No|E07=Yes}}
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{{family tree | | E01 | | E02 | | E03 | | E04 | | E05 | | E06 | | E07 | | |E01= Normal|E02= Osteoporosis|E03=[[Osteopenia]]|E04=[[Osteoporosis]]|E05=Severe [[osteoporosis]]|E06=Primary [[osteoporosis]]|E07=Secondary [[osteoporosis]]}}

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=== Osteoporosis classification based on disease etiology ===
On the basis of etiology, osteoporosis can be classified into:

==== Primary Osteoporosis ====
Primary [[osteoporosis]] develops as a result of [[aging]] or [[menopause]]-related [[bone]] demineralization. In patients with primary osteoporosis, the [[bone density]] decreases as the age progresses.

==== Secondary Osteoporosis ====
Secondary osteoporosis results from more severe [[Bone loss|loss of bone mass]] due to pathologies associated with immobilization, medications ([[iatrogenic]]), [[endocrine]] dysfunction, [[cancer]], and [[Chronic kidney diseas|chronic kidney disease]].<ref name="osteoporosis">{{cite book | last = Marcus | first = Robert | title = Osteoporosis | publisher = Elsevier/Academic Press | location = Amsterdam | year = 2013 | isbn = 9780124158535 }}</ref>

=== Osteoporosis classification based on disease severity ===
[[Osteoporosis]] may be classified based on the [[Bone mineral density|bone marrow density (BMD)]]. The patients are classified according to the site and method of measurements. The used equipment and reference group of people may also be helpful in classification of osteoporosis. The major value used in the classification of [[osteoporosis]] is T-score. T-score may be defined as "patient measured [[Bone mineral density|BMD]] value minus the reference [[Bone mineral density|BMD]] value (sex-matched and with a preference for youth) divided by the reference [[Standard deviation|standard deviation (SD)]] (sex-matched and with a preference for youth)".<ref name="pmid11341335">{{cite journal |vauthors=Lu Y, Genant HK, Shepherd J, Zhao S, Mathur A, Fuerst TP, Cummings SR |title=Classification of osteoporosis based on bone mineral densities |journal=J. Bone Miner. Res. |volume=16 |issue=5 |pages=901–10 |year=2001 |pmid=11341335 |doi=10.1359/jbmr.2001.16.5.901 |url=}}</ref> 

The classification of [[osteoporosis]] on the basis of [[Bone mineral density|BMD]] measured T-score is as follows:
* T-score less than -1 and more than -2.5: '''[[Osteopenia]]'''
* T-score equal to or less than -2.5: '''Osteoporosis'''
* T-score equal to or less than -2.5 with history of [[fracture]]: '''Severe [[osteoporosis]]'''
The exclusive utilization of T-score and comparing the reference normative data of people aged 20-29 years, as [[World health organization|world health organization (WHO)]] criteria, is very inconsistent. Compared to other classification systems, it is better to standardize the normative data, by including older people and individuals with other findings including [[Bone mineral density|BMD]] measurement at multiple sites, in order to obtain a comprehensive classification system.<ref name="pmid11341335">{{cite journal |vauthors=Lu Y, Genant HK, Shepherd J, Zhao S, Mathur A, Fuerst TP, Cummings SR |title=Classification of osteoporosis based on bone mineral densities |journal=J. Bone Miner. Res. |volume=16 |issue=5 |pages=901–10 |year=2001 |pmid=11341335 |doi=10.1359/jbmr.2001.16.5.901 |url=}}</ref>

=== Osteoporosis in children<ref name="BachrachGordon2016">{{cite journal|last1=Bachrach|first1=L. K.|last2=Gordon|first2=C. M.|title=Bone Densitometry in Children and Adolescents|journal=PEDIATRICS|volume=138|issue=4|year=2016|pages=e20162398–e20162398|issn=0031-4005|doi=10.1542/peds.2016-2398}}</ref> ===
* [[Bone mass]], as measured by [[DXA|DEXA]], is reported as bone mineral content (BMC) (g) or areal [[Bone mineral density|BMD]] (g/cm2). These values are compared to reference values from individuals of similar age, sex, and ethnicity to calculate the [[Z-score]], the number of [[Standard deviation|SD]]<nowiki/>s from the expected mean. Abundant pediatric reference data is now available for children and teenagers but not for [[infants]].
* It is essential to select norms collected by using equipment from the same manufacturer as that used for the patient because of systematic differences in software. Peak [[bone mass]] is achieved in the second or third decade, depending on the [[skeletal]] site. Therefore, T-scores (which compare the patient’s [[Bone mineral density|BMD]] with that of a healthy young adult) should not be used before 20 years of age.
* The appropriate interpretation of [[DXA|DEXA]] results may require more than the calculation of [[Z-score|Z-scores]]. 
* Children with chronic illness often have delayed growth and [[pubertal]] development, factors that contribute to a low [[bone mass]] for age or sex. [[Bone mineral density|BMD]], as measured by [[DXA|DEXA]], corrects [[Bone mineral density|bone mineral]] for the area (height and width) but not for the volume (height, width, and thickness) of [[bone]]. For this reason, if 2 individuals with identical “true” volumetric [[bone density]] are compared, the shorter person will have a lower [[Bone mineral density|BMD]] than the taller one. Similarly, a child with [[delayed puberty]] will not have had the gains in [[bone]] size, geometry, and density that occur with [[sex steroid]] exposure.
* Controversy persists about the optimal method to adjust for variations in [[bone]] size, body composition, and [[maturity]] as well as the criteria by which the “best method” is defined; ideally, the adjustment method would prove to be a stronger predictor of [[fracture]]. 
* The Pediatric Development Conference (PDC) guidelines recommend that [[Bone mineral density|BMD]] in children with delayed growth or puberty be adjusted for height or height age or compared with reference data with age, sex, and height-specific [[Z-score|Z-scores]].
* The terms “[[osteopenia]]” and “osteoporosis” are used in older adults to describe degree of deficits (lesser or greater) in [[bone mass]]. These terms should not be used to describe [[densitometry]] findings in pediatric patients. Instead, a BMC or [[Bone mineral density|BMD]] [[Z-score]] that is  > 2 [[Standard deviation|SD]]<nowiki/>s below expected (< - 2.0) is referred to as “'''''low for age'''''”.
* The following criteria for osteoporosis in a pediatric patient were agreed on in the 2013 PDC guidelines:<ref name="pmid24657108">{{cite journal |vauthors=Gordon CM, Leonard MB, Zemel BS |title=2013 Pediatric Position Development Conference: executive summary and reflections |journal=J Clin Densitom |volume=17 |issue=2 |pages=219–24 |year=2014 |pmid=24657108 |doi=10.1016/j.jocd.2014.01.007 |url=}}</ref>
** One or more [[vertebral fractures]] occurring in the absence of local disease or high-energy trauma (measuring [[Bone mineral density|BMD]] can add to the assessment of these patients but is not required as a diagnostic criterion);
** Low [[bone density]] (BMC or areal [[Bone mineral density|BMD]] [[Z-score|Z-scores]] <  - 2.0) and a significant [[fracture]] history (2 or more long [[bone fractures]] before 10 years of age or 3 or more long [[bone fractures]] before 19 years of age).
** Lastly, it is important to recognize that there are certain [[diseases]] in [[pediatric]] population (e.g., [[end-stage renal disease]] and spinal [[vertebral fractures]]) in which [[DXA|DEXA]] does not accurately reflect [[fracture]] risk or [[bone]] health.

=== Juvenile Osteoporosis (JO) ===
* [[Osteoporosis]] in children and adolescents is rare. Usually, it is due to some [[comorbidities]] or [[medications]] (secondary [[osteoporosis]]). Surprisingly, no significant causes have been found for rare cases ([[idiopathic]] [[osteoporosis]]).
* Irrespective of the cause, juvenile [[osteoporosis]] can be a significant problem because it occurs during the child’s prime [[bone]]-building years. From birth through young adulthood, children steadily accumulate [[bone mass]], which peaks, sometimes, before age 30. The greater their peak [[bone mass]], the lower their risk for [[osteoporosis]] later in life. After people reach their mid-thirties, bone mass typically begins to decline very slowly at first but the decline accelerates in their fifties and sixties. The [[lifestyle]] choices, especially the amount of [[calcium]] in the diet and the level of [[physical activity]] influence the development of peak [[bone mass]] and the rate at which [[bone]] is lost later in life.

==== Secondary Osteoporosis ====
* As the primary condition, [[juvenile idiopathic arthritis]] (also known as [[juvenile rheumatoid arthritis]]) provides a good illustration of the possible causes of secondary [[osteoporosis]]. In some cases, the disease process itself can cause [[osteoporosis]]. 
* In other cases, the medication used to treat the primary disorder may reduce [[bone mass]]. For example, drugs such as [[prednisone]] used to treat severe cases of [[juvenile idiopathic arthritis]], negatively affect [[bone mass]]. 
* Finally, some behaviors associated with the primary disorder may lead to [[bone loss]] or reduction in [[bone]] formation. For example, a child with juvenile idiopathic arthritis may avoid [[physical activity]], which is necessary for formation and maintainence [[bone mass]], because it may aggravate his or her condition or cause [[pain]].<ref name="urlJuvenile Osteoporosis" />
* For children with secondary [[osteoporosis]], the best course of action is to identify and treat the underlying disorder. In the case of [[medication]]-induced juvenile [[osteoporosis]], it is best to treat the primary disorder with the lowest effective dose of the [[osteoporosis]]-inducing [[medication]]. Like all children, those with secondary [[osteoporosis]] also need a diet rich in [[calcium]] and [[vitamin D]] and as much physical activity as possible given the limitations of the primary disorder.<ref name="urlJuvenile Osteoporosis" />

==== Idiopathic Juvenile Osteoporosis ====
* [[Idiopathic]] juvenile [[osteoporosis]] (IJO) is a primary condition with no known cause. It is diagnosed after other causes of juvenile [[osteoporosis]] have been excluded. This rare form of [[osteoporosis]] typically occurs just before the onset of [[puberty]] in previously healthy children. The average age at onset is 7 years, with a range of 1 to 13 years. Most of the children experience complete recovery of bone.

* The first sign of IJO is usually [[pain]] in the lower back, [[hips]], and [[feet]], often accompanied by difficulty walking. [[Knee]], [[ankle]] [[pain]] and [[fractures]] of the lower extremities may also occur. Physical malformations include [[kyphosis]], loss of height, a sunken chest, or a limp. These physical malformations are sometimes reversible after IJO has run its course.

* [[X-rays]] of children with IJO often show low [[bone density]], [[fractures]] of weight-bearing [[bones]], and collapsed or deformed [[vertebrae]]. However, conventional [[X-rays]] may not be able to detect [[osteoporosis]] until significant [[bone mass]] has occurred. Newer methods such as [[Dual energy X-ray absorptiometry|dual energy x-ray absorptiometry (DXA)]], and quantitative computed tomography (QCT ) allow for earlier and more accurate diagnosis of low [[bone mass]]. 

* There is no established [[medical]] or [[surgical]] therapy for juvenile [[osteoporosis]]. In some cases, no treatment may be needed because the condition usually goes away spontaneously. However, early diagnosis of juvenile [[osteoporosis]] is important so that steps can be taken to protect the child’s [[spine]] and other [[bones]] from [[fracture]] until remission occurs. These steps may include [[physical therapy]], use of [[crutches]], avoiding unsafe weight-bearing activities, and other supportive care. A well-balanced diet rich in [[calcium]] and [[vitamin D]] is also important. In severe, long-lasting cases of juvenile [[osteoporosis]], [[bisphosphonates]], approved by the [[Food and Drug Administration]] for the treatment of [[osteoporosis]] in adults, have been given to children experimentally.
* Most children with IJO experience complete recovery of [[bone]] tissue. Although growth may be somewhat impaired during the acute phase of the disorder, normal growth resumes and catch-up growth often occurs afterward. Unfortunately, in some cases, IJO can result in permanent disability such as [[kyphoscoliosis]] or collapse of the [[rib cage]].<ref name="urlJuvenile Osteoporosis">{{cite web |url=https://www.niams.nih.gov/health_info/bone/Bone_Health/Juvenile/juvenile_osteoporosis.asp |title=Juvenile Osteoporosis |format= |work= |accessdate=}}</ref>

==References==
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