Polymyositis and dermatomyositis laboratory findings: Difference between revisions
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==Overview== | ==Overview== | ||
Elevated [[Sarcoplasmic reticulum|sarcoplasmic]] enzymes are consistent with the diagnosis of polymyositis and dermatomyositis which include [[Creatine kinase|creatine phosphokinase]], [[aldolase]], [[Transaminase|transaminases]], [[Lactate dehydrogenase|lactic dehydrogenase]], and [[myoglobin]]. High [[White blood cells|white blood cell]] counts, low [[Lymphocyte|lymphocytes]], and low [[hematocrit]] levels might be detected on [[Complete blood count|CBC]]. Low [[albumin]] levels, high [[Erythrocyte sedimentation rate|ESR]] and high [[Immunoglobulin M|IgM]] and [[Immunoglobulin G|IgG]] levels could be seen in patients with polymyositis and dermatomyositis. 20 myositis-specific autoantibodies are identified in patients with polymyositis and dermatomyositis. Anti-Jo-1 antibody is the most frequent myositis-specific autoantibodies which causes antisynthetase syndrome. Anti Mi-2 might be seen frequently in patients with dermatomyositis. Anti-SRP antibody is associated with very poor prognosis. Some of these myositis-specific autoantibodies are associated with [[Cancer|malignancy]]. Anti-HMGCR antibody might be elevated in patients with statin-associated necrotizing autoimmune myopathy (SANAM). | |||
==Laboratory Findings== | ==Laboratory Findings== | ||
*Different laboratory tests may be used to diagnose polymyositis and dermatomyositis and exclude other myopathies which include:<ref name="pmid29579414">{{cite journal |vauthors=Adler BL, Christopher-Stine L |title=Triggers of inflammatory myopathy: insights into pathogenesis |journal=Discov Med |volume=25 |issue=136 |pages=75–83 |date=February 2018 |pmid=29579414 |doi= |url=}}</ref><ref name="pmid25182203">{{cite journal |vauthors=Bodoki L, Nagy-Vincze M, Griger Z, Betteridge Z, Szöllősi L, Dankó K |title=Four dermatomyositis-specific autoantibodies-anti-TIF1γ, anti-NXP2, anti-SAE and anti-MDA5-in adult and juvenile patients with idiopathic inflammatory myopathies in a Hungarian cohort |journal=Autoimmun Rev |volume=13 |issue=12 |pages=1211–9 |date=December 2014 |pmid=25182203 |doi=10.1016/j.autrev.2014.08.011 |url=}}</ref><ref name="KhanChristopher-Stine2011">{{cite journal|last1=Khan|first1=Sabiha|last2=Christopher-Stine|first2=Lisa|title=Polymyositis, Dermatomyositis, and Autoimmune Necrotizing Myopathy: Clinical Features|journal=Rheumatic Disease Clinics of North America|volume=37|issue=2|year=2011|pages=143–158|issn=0889857X|doi=10.1016/j.rdc.2011.01.001}}</ref><ref name="DoblougGaren2015">{{cite journal|last1=Dobloug|first1=Cecilie|last2=Garen|first2=Torhild|last3=Bitter|first3=Helle|last4=Stjärne|first4=Johan|last5=Stenseth|first5=Guri|last6=Grøvle|first6=Lars|last7=Sem|first7=Marthe|last8=Gran|first8=Jan Tore|last9=Molberg|first9=Øyvind|title=Prevalence and clinical characteristics of adult polymyositis and dermatomyositis; data from a large and unselected Norwegian cohort|journal=Annals of the Rheumatic Diseases|volume=74|issue=8|year=2015|pages=1551–1556|issn=0003-4967|doi=10.1136/annrheumdis-2013-205127}}</ref><ref name="ChinoyFertig2007">{{cite journal|last1=Chinoy|first1=H.|last2=Fertig|first2=N.|last3=Oddis|first3=C. V|last4=Ollier|first4=W. E R|last5=Cooper|first5=R. G|title=The diagnostic utility of myositis autoantibody testing for predicting the risk of cancer-associated myositis|journal=Annals of the Rheumatic Diseases|volume=66|issue=10|year=2007|pages=1345–1349|issn=0003-4967|doi=10.1136/ard.2006.068502}}</ref><ref name="DalakasHohlfeld2003">{{cite journal|last1=Dalakas|first1=Marinos C|last2=Hohlfeld|first2=Reinhard|title=Polymyositis and dermatomyositis|journal=The Lancet|volume=362|issue=9388|year=2003|pages=971–982|issn=01406736|doi=10.1016/S0140-6736(03)14368-1}}</ref><ref name="DouglasTazelaar2001">{{cite journal|last1=Douglas|first1=William W.|last2=Tazelaar|first2=Henry D.|last3=Hartman|first3=Thomas E.|last4=Hartman|first4=Robert P.|last5=Decker|first5=Paul A.|last6=Schroeder|first6=Darrell R.|last7=Ryu|first7=Jay H.|title=Polymyositis–Dermatomyositis-associated Interstitial Lung Disease|journal=American Journal of Respiratory and Critical Care Medicine|volume=164|issue=7|year=2001|pages=1182–1185|issn=1073-449X|doi=10.1164/ajrccm.164.7.2103110}}</ref><ref name="Miller1993">{{cite journal|last1=Miller|first1=Frederick W.|title=Myositis-Specific Autoantibodies|journal=JAMA|volume=270|issue=15|year=1993|pages=1846|issn=0098-7484|doi=10.1001/jama.1993.03510150080034}}</ref> | *Different laboratory tests may be used to diagnose polymyositis and dermatomyositis and exclude other myopathies which include:<ref name="pmid29579414">{{cite journal |vauthors=Adler BL, Christopher-Stine L |title=Triggers of inflammatory myopathy: insights into pathogenesis |journal=Discov Med |volume=25 |issue=136 |pages=75–83 |date=February 2018 |pmid=29579414 |doi= |url=}}</ref><ref name="pmid25182203">{{cite journal |vauthors=Bodoki L, Nagy-Vincze M, Griger Z, Betteridge Z, Szöllősi L, Dankó K |title=Four dermatomyositis-specific autoantibodies-anti-TIF1γ, anti-NXP2, anti-SAE and anti-MDA5-in adult and juvenile patients with idiopathic inflammatory myopathies in a Hungarian cohort |journal=Autoimmun Rev |volume=13 |issue=12 |pages=1211–9 |date=December 2014 |pmid=25182203 |doi=10.1016/j.autrev.2014.08.011 |url=}}</ref><ref name="KhanChristopher-Stine2011">{{cite journal|last1=Khan|first1=Sabiha|last2=Christopher-Stine|first2=Lisa|title=Polymyositis, Dermatomyositis, and Autoimmune Necrotizing Myopathy: Clinical Features|journal=Rheumatic Disease Clinics of North America|volume=37|issue=2|year=2011|pages=143–158|issn=0889857X|doi=10.1016/j.rdc.2011.01.001}}</ref><ref name="DoblougGaren2015">{{cite journal|last1=Dobloug|first1=Cecilie|last2=Garen|first2=Torhild|last3=Bitter|first3=Helle|last4=Stjärne|first4=Johan|last5=Stenseth|first5=Guri|last6=Grøvle|first6=Lars|last7=Sem|first7=Marthe|last8=Gran|first8=Jan Tore|last9=Molberg|first9=Øyvind|title=Prevalence and clinical characteristics of adult polymyositis and dermatomyositis; data from a large and unselected Norwegian cohort|journal=Annals of the Rheumatic Diseases|volume=74|issue=8|year=2015|pages=1551–1556|issn=0003-4967|doi=10.1136/annrheumdis-2013-205127}}</ref><ref name="ChinoyFertig2007">{{cite journal|last1=Chinoy|first1=H.|last2=Fertig|first2=N.|last3=Oddis|first3=C. V|last4=Ollier|first4=W. E R|last5=Cooper|first5=R. G|title=The diagnostic utility of myositis autoantibody testing for predicting the risk of cancer-associated myositis|journal=Annals of the Rheumatic Diseases|volume=66|issue=10|year=2007|pages=1345–1349|issn=0003-4967|doi=10.1136/ard.2006.068502}}</ref><ref name="DalakasHohlfeld2003">{{cite journal|last1=Dalakas|first1=Marinos C|last2=Hohlfeld|first2=Reinhard|title=Polymyositis and dermatomyositis|journal=The Lancet|volume=362|issue=9388|year=2003|pages=971–982|issn=01406736|doi=10.1016/S0140-6736(03)14368-1}}</ref><ref name="DouglasTazelaar2001">{{cite journal|last1=Douglas|first1=William W.|last2=Tazelaar|first2=Henry D.|last3=Hartman|first3=Thomas E.|last4=Hartman|first4=Robert P.|last5=Decker|first5=Paul A.|last6=Schroeder|first6=Darrell R.|last7=Ryu|first7=Jay H.|title=Polymyositis–Dermatomyositis-associated Interstitial Lung Disease|journal=American Journal of Respiratory and Critical Care Medicine|volume=164|issue=7|year=2001|pages=1182–1185|issn=1073-449X|doi=10.1164/ajrccm.164.7.2103110}}</ref><ref name="Miller1993">{{cite journal|last1=Miller|first1=Frederick W.|title=Myositis-Specific Autoantibodies|journal=JAMA|volume=270|issue=15|year=1993|pages=1846|issn=0098-7484|doi=10.1001/jama.1993.03510150080034}}</ref> | ||
**Sarcoplasmic enzymes | **Routine tests<ref name="Volochayev2012">{{cite journal|last1=Volochayev|first1=Rita|title=Laboratory Test Abnormalities are Common in Polymyositis and Dermatomyositis and Differ Among Clinical and Demographic Groups|journal=The Open Rheumatology Journal|volume=6|issue=1|year=2012|pages=54–63|issn=18743129|doi=10.2174/1874312901206010054}}</ref> | ||
**Myositis-specific autoantibodies<ref name="Targoff2006">{{cite journal|last1=Targoff|first1=Ira N.|title=Myositis specific autoantibodies|journal=Current Rheumatology Reports|volume=8|issue=3|year=2006|pages=196–203|issn=1523-3774|doi=10.1007/s11926-996-0025-3}}</ref> | **[[Endoplasmic reticulum|Sarcoplasmic]] enzymes | ||
**Myositis-specific autoantibodies<ref name="Targoff2006">{{cite journal|last1=Targoff|first1=Ira N.|title=Myositis specific autoantibodies|journal=Current Rheumatology Reports|volume=8|issue=3|year=2006|pages=196–203|issn=1523-3774|doi=10.1007/s11926-996-0025-3}}</ref><ref name="GunawardenaBetteridge2009">{{cite journal|last1=Gunawardena|first1=H.|last2=Betteridge|first2=Z. E.|last3=McHugh|first3=N. J.|title=Myositis-specific autoantibodies: their clinical and pathogenic significance in disease expression|journal=Rheumatology|volume=48|issue=6|year=2009|pages=607–612|issn=1462-0324|doi=10.1093/rheumatology/kep078}}</ref> | |||
=== Routine test === | |||
* Abnormal test results include: | |||
** [[Complete blood count|CBC]] | |||
*** High [[White blood cells|white blood cell]] counts | |||
*** Low [[lymphocyte]] counts | |||
*** Low [[hematocrit]] levels | |||
** Low [[albumin]] levels | |||
** High [[erythrocyte sedimentation rate]] | |||
** High [[Immunoglobulin M|IgM]] and [[Immunoglobulin G|IgG]] levels | |||
=== Sarcoplasmic enzymes === | === Sarcoplasmic enzymes === | ||
* Sarcoplasmic enzymes consistent with the diagnosis of polymyositis and dermatomyositis include:<ref name="BohanPeter1975">{{cite journal|last1=Bohan|first1=Anthony|last2=Peter|first2=James B.|title=Polymyositis and Dermatomyositis|journal=New England Journal of Medicine|volume=292|issue=8|year=1975|pages=403–407|issn=0028-4793|doi=10.1056/NEJM197502202920807}}</ref> | * [[Endoplasmic reticulum|Sarcoplasmic]] enzymes consistent with the diagnosis of polymyositis and dermatomyositis include:<ref name="BohanPeter1975">{{cite journal|last1=Bohan|first1=Anthony|last2=Peter|first2=James B.|title=Polymyositis and Dermatomyositis|journal=New England Journal of Medicine|volume=292|issue=8|year=1975|pages=403–407|issn=0028-4793|doi=10.1056/NEJM197502202920807}}</ref> | ||
** Creatine phosphokinase | ** [[Creatine kinase|Creatine phosphokinase]] including: | ||
** Aldolase | *** [[Creatine kinase|CK-MM]] | ||
** Transaminases | *** [[Creatine kinase|CK-MB]] | ||
** Lactic dehydrogenase | ** [[Aldolase]] | ||
** [[Transaminase|Transaminases]] | |||
*** [[Alanine transaminase|Alanine aminotransferase]] | |||
*** [[Aspartate transaminase|Aspartate aminotransferase]] | |||
** [[Lactate dehydrogenase|Lactic dehydrogenase]] | |||
** [[Myoglobin]] | |||
=== Myositis-specific autoantibodies === | === Myositis-specific autoantibodies === | ||
{| | {| | ||
! colspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |Autoantibody | ! colspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |Autoantibody | ||
Line 24: | Line 41: | ||
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Frequency | ! align="center" style="background:#4479BA; color: #FFFFFF;" + |Frequency | ||
|- | |- | ||
| rowspan=" | | rowspan="9" align="left" style="background:#F5F5F5;" + |Antisynthetase | ||
! align="left" style="background:#F5F5F5;" + |Anti-Jo-1 | |||
| align="left" style="background:#F5F5F5;" + |Histidyl-tRNA synthetase | | align="left" style="background:#F5F5F5;" + |Histidyl-tRNA synthetase | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
Line 40: | Line 57: | ||
| align="left" style="background:#F5F5F5;" + |20-25% | | align="left" style="background:#F5F5F5;" + |20-25% | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-PL-7 | |||
| align="left" style="background:#F5F5F5;" + |Threonyl-tRNA synthetase | | align="left" style="background:#F5F5F5;" + |Threonyl-tRNA synthetase | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
* Myositis, mechanic's hands, Gottron's papules, arthritis | * Myositis, mechanic's hands, Gottron's papules, arthritis | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + |5-10% | ||
|- | |- | ||
! rowspan="2" align="left" style="background:#F5F5F5;" + |Anti PL-12 | |||
| align="left" style="background:#F5F5F5;" + |Alanyl-tRNA synthetase | | align="left" style="background:#F5F5F5;" + |Alanyl-tRNA synthetase | ||
| rowspan="2" align="left" style="background:#F5F5F5;" + | | | rowspan="2" align="left" style="background:#F5F5F5;" + | | ||
* Fever, Raynaud's phenomenon, high frequency of ILD | * Fever, Raynaud's phenomenon, high frequency of ILD | ||
* Epstein-Barr virus (EBV), adenovirus, and influenza infection | * Epstein-Barr virus (EBV), adenovirus, and influenza infection | ||
| align="left" style="background:#F5F5F5;" + | | | rowspan="2" align="left" style="background:#F5F5F5;" + |<5% | ||
|- | |- | ||
| align="left" style="background:#F5F5F5;" + |Alanyl-tRNA | | align="left" style="background:#F5F5F5;" + |Alanyl-tRNA | ||
|- | |||
! align="left" style="background:#F5F5F5;" + |Anti-EJ | |||
| align="left" style="background:#F5F5F5;" + |Glycyl-tRNA synthetase | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |5-10% | |||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-OJ | |||
| align="left" style="background:#F5F5F5;" + |Isoleucyl-tRNA synthetase | | align="left" style="background:#F5F5F5;" + |Isoleucyl-tRNA synthetase | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |<5% | |||
|- | |||
! align="left" style="background:#F5F5F5;" + |Anti-KS | |||
| align="left" style="background:#F5F5F5;" + |Asparaginyl-tRNA synthetase | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |<5% | |||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-Ha | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + |Tyrosyl-tRNA synthetase | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |<1% | |||
|- | |||
! align="left" style="background:#F5F5F5;" + |Anti-Zo | |||
| align="left" style="background:#F5F5F5;" + |Phenylalanyl-tRNA synthetase | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |<1% | |||
|- | |- | ||
| | | rowspan="12" align="left" style="background:#F5F5F5;" + |Others | ||
! align="left" style="background:#F5F5F5;" + |Anti Mi-2 | |||
| align="left" style="background:#F5F5F5;" + |Chromodomain helicase DNA binding protein 4 | | align="left" style="background:#F5F5F5;" + |Chromodomain helicase DNA binding protein 4 | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
Line 93: | Line 106: | ||
| align="left" style="background:#F5F5F5;" + |5-10% | | align="left" style="background:#F5F5F5;" + |5-10% | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-SRP | |||
| align="left" style="background:#F5F5F5;" + |Signal recognition particle | | align="left" style="background:#F5F5F5;" + |Signal recognition particle | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
* Cardiac involvement | * Cardiac involvement | ||
* Necrotizing myopathy | |||
* Flare up in fall | * Flare up in fall | ||
* Very acute and severe onset | * Very acute and severe onset | ||
Line 104: | Line 117: | ||
| align="left" style="background:#F5F5F5;" + |<5% | | align="left" style="background:#F5F5F5;" + |<5% | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-p155/140 | |||
| align="left" style="background:#F5F5F5;" + |Transcriptional intermediary factor 1-gamma | | align="left" style="background:#F5F5F5;" + |Transcriptional intermediary factor 1-gamma | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
Line 122: | Line 127: | ||
23-29% in JDM | 23-29% in JDM | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-MJ | |||
| align="left" style="background:#F5F5F5;" + |Nuclear matrix protein (NXP-2) | |||
| align="left" style="background:#F5F5F5;" + |Nuclear matrix protein | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
* Cancer-associated myositis | * Cancer-associated myositis | ||
Line 130: | Line 134: | ||
| align="left" style="background:#F5F5F5;" + |23% in JDM | | align="left" style="background:#F5F5F5;" + |23% in JDM | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-SAE | |||
| align="left" style="background:#F5F5F5;" + |Small ubiquitin-like modifier activating enzyme | |||
| align="left" style="background:#F5F5F5;" + | | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
* Cancer-associated myositis | * Cancer-associated myositis | ||
| align="left" style="background:#F5F5F5;" + |5% | | align="left" style="background:#F5F5F5;" + |5% | ||
|- | |- | ||
| | ! align="left" style="background:#F5F5F5;" + |Anti-caDM-140 | ||
| align="left" style="background:#F5F5F5;" + |Intracytoplasmic MDA5 | |||
|Intracytoplasmic MDA5 | | align="left" style="background:#F5F5F5;" + | | ||
| | |||
* Dermatomyositis and rapidly progressive ILD | * Dermatomyositis and rapidly progressive ILD | ||
| | | align="left" style="background:#F5F5F5;" + |50% (C-ADM) | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-PMS1 | |||
| align="left" style="background:#F5F5F5;" + |DNA mismatch repair enzyme | |||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + |Anti HMGCR | | align="left" style="background:#F5F5F5;" + |7.5% | ||
|- | |||
! align="left" style="background:#F5F5F5;" + |Anti-HMGCR | |||
| align="left" style="background:#F5F5F5;" + |3-hydroxy-3-methylglutaryl-coenzyme A reductase | | align="left" style="background:#F5F5F5;" + |3-hydroxy-3-methylglutaryl-coenzyme A reductase | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
Line 151: | Line 157: | ||
| align="left" style="background:#F5F5F5;" + |6% | | align="left" style="background:#F5F5F5;" + |6% | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-FER | |||
| align="left" style="background:#F5F5F5;" + |Elongation factor 1 alpha | | align="left" style="background:#F5F5F5;" + |Elongation factor 1 alpha | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-KJ | |||
| align="left" style="background:#F5F5F5;" + |Unidentified cytoplasmic protein | | align="left" style="background:#F5F5F5;" + |Unidentified cytoplasmic protein | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
|- | |- | ||
! align="left" style="background:#F5F5F5;" + |Anti-MAS | |||
| align="left" style="background:#F5F5F5;" + |Unidentified cytoplasmic RNA | | align="left" style="background:#F5F5F5;" + |Unidentified cytoplasmic RNA | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
| align="left" style="background:#F5F5F5;" + | | | align="left" style="background:#F5F5F5;" + | | ||
|- | |- | ||
| | ! align="left" style="background:#F5F5F5;" + |Anti–PM-Scl | ||
| | | align="left" style="background:#F5F5F5;" + | | ||
| | | align="left" style="background:#F5F5F5;" + | | ||
| | * Overlap of polymyositis and Scleroderma | ||
| | | align="left" style="background:#F5F5F5;" + |25% | ||
|} | |} | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} |
Latest revision as of 13:20, 4 June 2018
Polymyositis and dermatomyositis Microchapters |
Differentiating Polymyositis and dermatomyositis from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]
Overview
Elevated sarcoplasmic enzymes are consistent with the diagnosis of polymyositis and dermatomyositis which include creatine phosphokinase, aldolase, transaminases, lactic dehydrogenase, and myoglobin. High white blood cell counts, low lymphocytes, and low hematocrit levels might be detected on CBC. Low albumin levels, high ESR and high IgM and IgG levels could be seen in patients with polymyositis and dermatomyositis. 20 myositis-specific autoantibodies are identified in patients with polymyositis and dermatomyositis. Anti-Jo-1 antibody is the most frequent myositis-specific autoantibodies which causes antisynthetase syndrome. Anti Mi-2 might be seen frequently in patients with dermatomyositis. Anti-SRP antibody is associated with very poor prognosis. Some of these myositis-specific autoantibodies are associated with malignancy. Anti-HMGCR antibody might be elevated in patients with statin-associated necrotizing autoimmune myopathy (SANAM).
Laboratory Findings
- Different laboratory tests may be used to diagnose polymyositis and dermatomyositis and exclude other myopathies which include:[1][2][3][4][5][6][7][8]
- Routine tests[9]
- Sarcoplasmic enzymes
- Myositis-specific autoantibodies[10][11]
Routine test
- Abnormal test results include:
- CBC
- High white blood cell counts
- Low lymphocyte counts
- Low hematocrit levels
- Low albumin levels
- High erythrocyte sedimentation rate
- High IgM and IgG levels
- CBC
Sarcoplasmic enzymes
- Sarcoplasmic enzymes consistent with the diagnosis of polymyositis and dermatomyositis include:[12]
Myositis-specific autoantibodies
Autoantibody | Antigen | Features | Frequency | |
---|---|---|---|---|
Antisynthetase | Anti-Jo-1 | Histidyl-tRNA synthetase |
|
20-25% |
Anti-PL-7 | Threonyl-tRNA synthetase |
|
5-10% | |
Anti PL-12 | Alanyl-tRNA synthetase |
|
<5% | |
Alanyl-tRNA | ||||
Anti-EJ | Glycyl-tRNA synthetase | 5-10% | ||
Anti-OJ | Isoleucyl-tRNA synthetase | <5% | ||
Anti-KS | Asparaginyl-tRNA synthetase | <5% | ||
Anti-Ha | Tyrosyl-tRNA synthetase | <1% | ||
Anti-Zo | Phenylalanyl-tRNA synthetase | <1% | ||
Others | Anti Mi-2 | Chromodomain helicase DNA binding protein 4 |
|
5-10% |
Anti-SRP | Signal recognition particle |
|
<5% | |
Anti-p155/140 | Transcriptional intermediary factor 1-gamma |
|
13-21% in IIM
23-29% in JDM | |
Anti-MJ | Nuclear matrix protein (NXP-2) |
|
23% in JDM | |
Anti-SAE | Small ubiquitin-like modifier activating enzyme |
|
5% | |
Anti-caDM-140 | Intracytoplasmic MDA5 |
|
50% (C-ADM) | |
Anti-PMS1 | DNA mismatch repair enzyme | 7.5% | ||
Anti-HMGCR | 3-hydroxy-3-methylglutaryl-coenzyme A reductase |
|
6% | |
Anti-FER | Elongation factor 1 alpha | |||
Anti-KJ | Unidentified cytoplasmic protein | |||
Anti-MAS | Unidentified cytoplasmic RNA | |||
Anti–PM-Scl |
|
25% |
References
- ↑ Adler BL, Christopher-Stine L (February 2018). "Triggers of inflammatory myopathy: insights into pathogenesis". Discov Med. 25 (136): 75–83. PMID 29579414.
- ↑ Bodoki L, Nagy-Vincze M, Griger Z, Betteridge Z, Szöllősi L, Dankó K (December 2014). "Four dermatomyositis-specific autoantibodies-anti-TIF1γ, anti-NXP2, anti-SAE and anti-MDA5-in adult and juvenile patients with idiopathic inflammatory myopathies in a Hungarian cohort". Autoimmun Rev. 13 (12): 1211–9. doi:10.1016/j.autrev.2014.08.011. PMID 25182203.
- ↑ Khan, Sabiha; Christopher-Stine, Lisa (2011). "Polymyositis, Dermatomyositis, and Autoimmune Necrotizing Myopathy: Clinical Features". Rheumatic Disease Clinics of North America. 37 (2): 143–158. doi:10.1016/j.rdc.2011.01.001. ISSN 0889-857X.
- ↑ Dobloug, Cecilie; Garen, Torhild; Bitter, Helle; Stjärne, Johan; Stenseth, Guri; Grøvle, Lars; Sem, Marthe; Gran, Jan Tore; Molberg, Øyvind (2015). "Prevalence and clinical characteristics of adult polymyositis and dermatomyositis; data from a large and unselected Norwegian cohort". Annals of the Rheumatic Diseases. 74 (8): 1551–1556. doi:10.1136/annrheumdis-2013-205127. ISSN 0003-4967.
- ↑ Chinoy, H.; Fertig, N.; Oddis, C. V; Ollier, W. E R; Cooper, R. G (2007). "The diagnostic utility of myositis autoantibody testing for predicting the risk of cancer-associated myositis". Annals of the Rheumatic Diseases. 66 (10): 1345–1349. doi:10.1136/ard.2006.068502. ISSN 0003-4967.
- ↑ Dalakas, Marinos C; Hohlfeld, Reinhard (2003). "Polymyositis and dermatomyositis". The Lancet. 362 (9388): 971–982. doi:10.1016/S0140-6736(03)14368-1. ISSN 0140-6736.
- ↑ Douglas, William W.; Tazelaar, Henry D.; Hartman, Thomas E.; Hartman, Robert P.; Decker, Paul A.; Schroeder, Darrell R.; Ryu, Jay H. (2001). "Polymyositis–Dermatomyositis-associated Interstitial Lung Disease". American Journal of Respiratory and Critical Care Medicine. 164 (7): 1182–1185. doi:10.1164/ajrccm.164.7.2103110. ISSN 1073-449X.
- ↑ Miller, Frederick W. (1993). "Myositis-Specific Autoantibodies". JAMA. 270 (15): 1846. doi:10.1001/jama.1993.03510150080034. ISSN 0098-7484.
- ↑ Volochayev, Rita (2012). "Laboratory Test Abnormalities are Common in Polymyositis and Dermatomyositis and Differ Among Clinical and Demographic Groups". The Open Rheumatology Journal. 6 (1): 54–63. doi:10.2174/1874312901206010054. ISSN 1874-3129.
- ↑ Targoff, Ira N. (2006). "Myositis specific autoantibodies". Current Rheumatology Reports. 8 (3): 196–203. doi:10.1007/s11926-996-0025-3. ISSN 1523-3774.
- ↑ Gunawardena, H.; Betteridge, Z. E.; McHugh, N. J. (2009). "Myositis-specific autoantibodies: their clinical and pathogenic significance in disease expression". Rheumatology. 48 (6): 607–612. doi:10.1093/rheumatology/kep078. ISSN 1462-0324.
- ↑ Bohan, Anthony; Peter, James B. (1975). "Polymyositis and Dermatomyositis". New England Journal of Medicine. 292 (8): 403–407. doi:10.1056/NEJM197502202920807. ISSN 0028-4793.