ESR - Revision history

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← Older revision		Revision as of 06:44, 22 March 2026
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	[[Category:ID]]		[[Category:ID]]
			[[Category:Labs]]

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2026-03-19T15:52:52Z

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← Older revision		Revision as of 15:52, 19 March 2026
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	The erythrocyte sedimentation rate (ESR, sed rate) is a nonspecific marker of systemic inflammation that measures how quickly red blood cells settle in a standardized tube over one hour. It is inexpensive and widely available but has limited sensitivity and specificity for any single diagnosis. In the ED, its primary utility is in the evaluation of [[temporal arteritis]], [[polymyalgia rheumatica]], back pain concerning for spinal infection, and as an adjunct in the workup of [[septic arthritis]] and [[osteomyelitis]].<ref name="StatPearls">Tishkowski K, Zubair M. Erythrocyte Sedimentation Rate. ''StatPearls''. NCBI Bookshelf. Updated July 2025.</ref>		==Background==
			*The erythrocyte sedimentation rate (ESR, sed rate) is a nonspecific marker of systemic inflammation that measures how quickly red blood cells settle in a standardized tube over one hour.
			*It is inexpensive and widely available but has limited sensitivity and specificity for any single diagnosis.
			*In the ED, its primary utility is in the evaluation of [[temporal arteritis]], [[polymyalgia rheumatica]], back pain concerning for spinal infection, and as an adjunct in the workup of [[septic arthritis]] and [[osteomyelitis]].<ref name="StatPearls">Tishkowski K, Zubair M.
			*Erythrocyte Sedimentation Rate. ''StatPearls''.
			*NCBI Bookshelf.
			*Updated July 2025.</ref>


	~~==Background==~~
	*Measures the rate (mm/hr) at which RBCs fall in anticoagulated blood over 1 hour (Westergren method)<ref name="StatPearls"/>		*Measures the rate (mm/hr) at which RBCs fall in anticoagulated blood over 1 hour (Westergren method)<ref name="StatPearls"/>
	*Inflammation increases fibrinogen and immunoglobulins, which promote RBC aggregation into rouleaux formations — these larger aggregates settle faster, elevating the ESR<ref name="StatPearls"/>		*Inflammation increases fibrinogen and immunoglobulins, which promote RBC aggregation into rouleaux formations — these larger aggregates settle faster, elevating the ESR<ref name="StatPearls"/>
Line 8:		Line 14:

	===Normal Values (Westergren method)===		===Normal Values (Westergren method)===
	*~~'''~~Males:~~'''~~ Age/2 (mm/hr)		*Males: Age/2 (mm/hr)
	*~~'''~~Females:~~'''~~ (Age + 10)/2 (mm/hr)		*Females: (Age + 10)/2 (mm/hr)
	*General reference ranges:<ref name="StatPearls"/>		*General reference ranges:<ref name="StatPearls"/>
	**Males <50 years: 0–15 mm/hr		**Males <50 years: 0–15 mm/hr
Line 20:		Line 26:
	ESR is not ordered based on specific clinical features of the ESR itself — rather it is ordered as an '''adjunct''' to the clinical evaluation of underlying disease. Consider ESR in the following ED presentations:		ESR is not ordered based on specific clinical features of the ESR itself — rather it is ordered as an '''adjunct''' to the clinical evaluation of underlying disease. Consider ESR in the following ED presentations:

	*~~'''~~New headache in a patient >50 years~~'''~~ — [[temporal arteritis]] evaluation		*New headache in a patient >50 years — [[temporal arteritis]] evaluation
	*~~'''~~Proximal muscle stiffness and pain in a patient >50 years~~'''~~ — [[polymyalgia rheumatica]]		*Proximal muscle stiffness and pain in a patient >50 years — [[polymyalgia rheumatica]]
	*~~'''~~Back pain with red flags~~'''~~ (fever, IVDU, immunosuppression, recent bacteremia) — [[spinal epidural abscess]], vertebral [[osteomyelitis]]		*Back pain with red flags (fever, IVDU, immunosuppression, recent bacteremia) — [[spinal epidural abscess]], vertebral [[osteomyelitis]]
	*~~'''~~Acute monoarticular joint pain~~'''~~ — as part of [[septic arthritis]] workup (but does not replace [[arthrocentesis]])		*Acute monoarticular joint pain — as part of [[septic arthritis]] workup (but does not replace [[arthrocentesis]])
	*~~'''~~Prosthetic joint concern for infection~~'''~~ — as part of periprosthetic joint infection (PJI) evaluation		*Prosthetic joint concern for infection — as part of periprosthetic joint infection (PJI) evaluation
	*~~'''~~Fever of unknown origin~~'''~~ — as a nonspecific screening tool		*Fever of unknown origin — as a nonspecific screening tool
	*~~'''~~Suspected malignancy~~'''~~ — [[multiple myeloma]], [[lymphoma]], metastatic disease		*Suspected malignancy — [[multiple myeloma]], [[lymphoma]], metastatic disease

	==Differential Diagnosis==		==Differential Diagnosis==
	===Causes of Elevated ESR===		===Causes of Elevated ESR===
	*~~'''~~Infection:~~'''~~ Bacterial infections (especially chronic: osteomyelitis, endocarditis, TB, abscess), some viral infections		*Infection: Bacterial infections (especially chronic: osteomyelitis, endocarditis, TB, abscess), some viral infections
	*~~'''~~Autoimmune/inflammatory:~~'''~~ [[Temporal arteritis]], [[polymyalgia rheumatica]], [[rheumatoid arthritis]], [[systemic lupus erythematosus]], vasculitis, inflammatory bowel disease		*Autoimmune/inflammatory: [[Temporal arteritis]], [[polymyalgia rheumatica]], [[rheumatoid arthritis]], [[systemic lupus erythematosus]], vasculitis, inflammatory bowel disease
	*~~'''~~Malignancy:~~'''~~ [[Multiple myeloma]], [[lymphoma]], metastatic solid tumors		*Malignancy: [[Multiple myeloma]], [[lymphoma]], metastatic solid tumors
	*~~'''~~Other:~~'''~~ [[Anemia]], pregnancy, obesity, [[chronic kidney disease]], ESRD, diabetes, advanced age, female sex, hyperlipidemia, elevated fibrinogen states		*Other: [[Anemia]], pregnancy, obesity, [[chronic kidney disease]], ESRD, diabetes, advanced age, female sex, hyperlipidemia, elevated fibrinogen states
	*~~'''~~Medications:~~'''~~ Oral contraceptives, heparin, dextran, methyldopa, vitamin A		*Medications: Oral contraceptives, heparin, dextran, methyldopa, vitamin A

	===Causes of Low/Falsely Normal ESR===		===Causes of Low/Falsely Normal ESR===
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	*Consider further imaging (MRI) if ESR >20 mm/hr and CRP >1 mg/dL with concerning history		*Consider further imaging (MRI) if ESR >20 mm/hr and CRP >1 mg/dL with concerning history
	*ESR can be >100 mm/hr in vertebral osteomyelitis		*ESR can be >100 mm/hr in vertebral osteomyelitis
	*~~'''~~Normal ESR does NOT rule out~~'''~~ epidural abscess or osteomyelitis in high-risk patients — proceed to MRI if clinical suspicion is high		*Normal ESR does NOT rule out epidural abscess or osteomyelitis in high-risk patients — proceed to MRI if clinical suspicion is high

	'''Septic arthritis:'''<ref name="emDocs"/>		'''Septic arthritis:'''<ref name="emDocs"/>
	*ESR >15 mm/hr and CRP >2 mg/dL are >90% sensitive for septic arthritis		*ESR >15 mm/hr and CRP >2 mg/dL are >90% sensitive for septic arthritis
	*However, this is '''not specific''' — many inflammatory arthropathies cause similar elevations		*However, this is '''not specific''' — many inflammatory arthropathies cause similar elevations
	*~~'''~~ESR and CRP should not change the decision to perform [[arthrocentesis]]~~'''~~ when septic arthritis is suspected		*ESR and CRP should not change the decision to perform [[arthrocentesis]] when septic arthritis is suspected

	'''Temporal arteritis (giant cell arteritis):'''		'''Temporal arteritis (giant cell arteritis):'''
	*ACR classification criteria include ESR ≥50 mm/hr		*ACR classification criteria include ESR ≥50 mm/hr
	*CRP may be '''more sensitive''' than ESR for biopsy-positive GCA<ref name="Kermani">Kermani TA, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. ''Semin Arthritis Rheum''. 2012;41(6):866-871.</ref>		*CRP may be '''more sensitive''' than ESR for biopsy-positive GCA<ref name="Kermani">Kermani TA, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. ''Semin Arthritis Rheum''. 2012;41(6):866-871.</ref>
	*~~'''~~~10% of biopsy-proven GCA cases have normal ESR and CRP at diagnosis~~'''~~ — a normal ESR does '''NOT''' exclude the diagnosis if clinical suspicion is high<ref name="Kermani"/>		*~10% of biopsy-proven GCA cases have normal ESR and CRP at diagnosis — a normal ESR does '''NOT''' exclude the diagnosis if clinical suspicion is high<ref name="Kermani"/>
	*Polycythemia and elevated hematocrit can falsely lower ESR in patients with GCA<ref name="NormalGCA">Ganiats TG, et al. Temporal arteritis with normal erythrocyte sedimentation rate. ''J Am Board Fam Pract''. 1991;4(2):119-122.</ref>		*Polycythemia and elevated hematocrit can falsely lower ESR in patients with GCA<ref name="NormalGCA">Ganiats TG, et al. Temporal arteritis with normal erythrocyte sedimentation rate. ''J Am Board Fam Pract''. 1991;4(2):119-122.</ref>

Ostermayer: Created page with "The erythrocyte sedimentation rate (ESR, sed rate) is a nonspecific marker of systemic inflammation that measures how quickly red blood cells settle in a standardized tube over one hour. It is inexpensive and widely available but has limited sensitivity and specificity for any single diagnosis. In the ED, its primary utility is in the evaluation of temporal arteritis, polymyalgia rheumatica, back pain concerning for spinal infection, and as an adjunct in the work..."

2026-03-10T23:34:36Z

Created page with "The erythrocyte sedimentation rate (ESR, sed rate) is a nonspecific marker of systemic inflammation that measures how quickly red blood cells settle in a standardized tube over one hour. It is inexpensive and widely available but has limited sensitivity and specificity for any single diagnosis. In the ED, its primary utility is in the evaluation of temporal arteritis, polymyalgia rheumatica, back pain concerning for spinal infection, and as an adjunct in the work..."

New page

The erythrocyte sedimentation rate (ESR, sed rate) is a nonspecific marker of systemic inflammation that measures how quickly red blood cells settle in a standardized tube over one hour. It is inexpensive and widely available but has limited sensitivity and specificity for any single diagnosis. In the ED, its primary utility is in the evaluation of [[temporal arteritis]], [[polymyalgia rheumatica]], back pain concerning for spinal infection, and as an adjunct in the workup of [[septic arthritis]] and [[osteomyelitis]].<ref name="StatPearls">Tishkowski K, Zubair M. Erythrocyte Sedimentation Rate. ''StatPearls''. NCBI Bookshelf. Updated July 2025.</ref>

==Background==
*Measures the rate (mm/hr) at which RBCs fall in anticoagulated blood over 1 hour (Westergren method)<ref name="StatPearls"/>
*Inflammation increases fibrinogen and immunoglobulins, which promote RBC aggregation into rouleaux formations — these larger aggregates settle faster, elevating the ESR<ref name="StatPearls"/>
*ESR rises 24–48 hours after onset of acute inflammation and may take '''weeks to months''' to normalize — it is a '''slow-moving''' marker compared to CRP (which rises within hours and falls within days)<ref name="Wiki">Erythrocyte sedimentation rate. ''Wikipedia''. Accessed 2025.</ref>
*ESR >100 mm/hr has a ~90% probability of an identifiable underlying cause (most commonly infection, collagen vascular disease, or malignancy)<ref name="AAFP">Brigden ML. Clinical utility of the erythrocyte sedimentation rate. ''Am Fam Physician''. 1999;60(5):1443-1450.</ref>

===Normal Values (Westergren method)===
*'''Males:''' Age/2 (mm/hr)
*'''Females:''' (Age + 10)/2 (mm/hr)
*General reference ranges:<ref name="StatPearls"/>
**Males <50 years: 0–15 mm/hr
**Males >50 years: 0–20 mm/hr
**Females <50 years: 0–20 mm/hr
**Females >50 years: 0–30 mm/hr
**Children: 0–10 mm/hr

==Clinical Features==
ESR is not ordered based on specific clinical features of the ESR itself — rather it is ordered as an '''adjunct''' to the clinical evaluation of underlying disease. Consider ESR in the following ED presentations:

*'''New headache in a patient >50 years''' — [[temporal arteritis]] evaluation
*'''Proximal muscle stiffness and pain in a patient >50 years''' — [[polymyalgia rheumatica]]
*'''Back pain with red flags''' (fever, IVDU, immunosuppression, recent bacteremia) — [[spinal epidural abscess]], vertebral [[osteomyelitis]]
*'''Acute monoarticular joint pain''' — as part of [[septic arthritis]] workup (but does not replace [[arthrocentesis]])
*'''Prosthetic joint concern for infection''' — as part of periprosthetic joint infection (PJI) evaluation
*'''Fever of unknown origin''' — as a nonspecific screening tool
*'''Suspected malignancy''' — [[multiple myeloma]], [[lymphoma]], metastatic disease

==Differential Diagnosis==
===Causes of Elevated ESR===
*'''Infection:''' Bacterial infections (especially chronic: osteomyelitis, endocarditis, TB, abscess), some viral infections
*'''Autoimmune/inflammatory:''' [[Temporal arteritis]], [[polymyalgia rheumatica]], [[rheumatoid arthritis]], [[systemic lupus erythematosus]], vasculitis, inflammatory bowel disease
*'''Malignancy:''' [[Multiple myeloma]], [[lymphoma]], metastatic solid tumors
*'''Other:''' [[Anemia]], pregnancy, obesity, [[chronic kidney disease]], ESRD, diabetes, advanced age, female sex, hyperlipidemia, elevated fibrinogen states
*'''Medications:''' Oral contraceptives, heparin, dextran, methyldopa, vitamin A

===Causes of Low/Falsely Normal ESR===
*[[Polycythemia vera]] (increased viscosity slows sedimentation)
*[[Sickle cell disease]] (abnormal RBC shape impairs rouleaux)
*Severe [[leukocytosis]]
*[[Congestive heart failure]]
*Hypofibrinogenemia, DIC
*Cachexia, low albumin states
*Medications: Aspirin, NSAIDs, corticosteroids, quinine
*Habitual exercise, regular alcohol use<ref name="StatPearls"/>

==Evaluation==
===Workup===
*ESR is a '''venous blood test''' — no special patient preparation required
*Order alongside '''CRP''' for improved diagnostic utility — CRP rises/falls faster and is more specific for acute inflammation<ref name="emDocs">Erythrocyte Sedimentation Rate and C-Reactive Protein in the ED. ''emDocs''. December 2023.</ref>
*'''Do not routinely order ESR''' in undifferentiated patients — it is nonspecific and false positives are distracting<ref name="emDocs"/>
*ESR turnaround is typically 1 hour (inherent to the test methodology), making it '''slower than CRP''' in most labs

===Diagnosis===
ESR does not diagnose any specific disease. Interpret in context:

'''Back pain (spinal epidural abscess / vertebral osteomyelitis):'''<ref name="emDocs"/>
*ESR and CRP are elevated in 94–100% of spinal infections, often in the absence of leukocytosis
*Consider further imaging (MRI) if ESR >20 mm/hr and CRP >1 mg/dL with concerning history
*ESR can be >100 mm/hr in vertebral osteomyelitis
*'''Normal ESR does NOT rule out''' epidural abscess or osteomyelitis in high-risk patients — proceed to MRI if clinical suspicion is high

'''Septic arthritis:'''<ref name="emDocs"/>
*ESR >15 mm/hr and CRP >2 mg/dL are >90% sensitive for septic arthritis
*However, this is '''not specific''' — many inflammatory arthropathies cause similar elevations
*'''ESR and CRP should not change the decision to perform [[arthrocentesis]]''' when septic arthritis is suspected

'''Temporal arteritis (giant cell arteritis):'''
*ACR classification criteria include ESR ≥50 mm/hr
*CRP may be '''more sensitive''' than ESR for biopsy-positive GCA<ref name="Kermani">Kermani TA, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. ''Semin Arthritis Rheum''. 2012;41(6):866-871.</ref>
*'''~10% of biopsy-proven GCA cases have normal ESR and CRP at diagnosis''' — a normal ESR does '''NOT''' exclude the diagnosis if clinical suspicion is high<ref name="Kermani"/>
*Polycythemia and elevated hematocrit can falsely lower ESR in patients with GCA<ref name="NormalGCA">Ganiats TG, et al. Temporal arteritis with normal erythrocyte sedimentation rate. ''J Am Board Fam Pract''. 1991;4(2):119-122.</ref>

'''Osteomyelitis:'''
*ESR is elevated in >90% of cases of spondylodiscitis<ref name="APR">Becker KL, et al. Acute phase reactants in infections: evidence-based review and a guide for clinicians. ''Open Forum Infect Dis''. 2015;2(3):ofv098.</ref>
*ESR remains elevated for weeks to months after treatment initiation (useful for monitoring but not for early treatment response — use CRP for that)

'''ESR >100 mm/hr:'''<ref name="AAFP"/>
*Strongly suggests serious underlying disease (~90% will have an identifiable cause)
*Most common: Infection (including abscess, endocarditis, osteomyelitis), malignancy (especially myeloma, lymphoma), autoimmune disease (GCA, SLE)

==Management==
*ESR is a '''diagnostic adjunct''' — management is directed at the underlying condition identified
*'''Do not treat an elevated ESR in isolation''' — pursue the clinical diagnosis
*'''Do not use a normal ESR to exclude dangerous diagnoses''' in high-risk patients — proceed with definitive workup (MRI, arthrocentesis, temporal artery biopsy) when clinical suspicion warrants
*For monitoring purposes (e.g., GCA, PMR, osteomyelitis), ESR is useful for tracking disease activity over time — declining ESR suggests treatment response

==Disposition==
*Disposition depends on the underlying diagnosis, not the ESR value itself
*An incidentally elevated ESR in an otherwise well-appearing patient with a benign clinical picture does '''not''' require ED admission — arrange outpatient follow-up for repeat testing and further evaluation
*ESR >100 mm/hr warrants an identifiable explanation before discharge, or close outpatient follow-up with primary care or appropriate specialist

==See Also==
*[[Temporal arteritis]]
*[[Polymyalgia rheumatica]]
*[[Septic arthritis]]
*[[Osteomyelitis]]
*[[Spinal epidural abscess]]
*[[Multiple myeloma]]

==External Links==
*[https://www.emdocs.net/erythrocyte-sedimentation-rate-and-c-reactive-protein-in-the-ed/ emDocs: ESR and CRP in the ED]

==References==
{{reflist|2}}

[[Category:ID]]

← Older revision		Revision as of 09:38, 22 March 2026
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	*Measures the rate (mm/hr) at which RBCs fall in anticoagulated blood over 1 hour (Westergren method)<ref name="StatPearls"/>		*Measures the rate (mm/hr) at which RBCs fall in anticoagulated blood over 1 hour (Westergren method)<ref name="StatPearls"/>
	*Inflammation increases fibrinogen and immunoglobulins, which promote RBC aggregation into rouleaux formations — these larger aggregates settle faster, elevating the ESR<ref name="StatPearls"/>		*Inflammation increases fibrinogen and immunoglobulins, which promote RBC aggregation into rouleaux formations — these larger aggregates settle faster, elevating the ESR<ref name="StatPearls"/>
	*ESR rises 24–48 hours after onset of acute inflammation and may take ~~'''~~weeks to months~~'''~~ to normalize — it is a ~~'''~~slow-moving~~'''~~ marker compared to CRP (which rises within hours and falls within days)<ref name="Wiki">Erythrocyte sedimentation rate. ''Wikipedia''. Accessed 2025.</ref>		*ESR rises 24–48 hours after onset of acute inflammation and may take weeks to months to normalize — it is a slow-moving marker compared to CRP (which rises within hours and falls within days)<ref name="Wiki">Erythrocyte sedimentation rate. ''Wikipedia''. Accessed 2025.</ref>
	*ESR >100 mm/hr has a ~90% probability of an identifiable underlying cause (most commonly infection, collagen vascular disease, or malignancy)<ref name="AAFP">Brigden ML. Clinical utility of the erythrocyte sedimentation rate. ''Am Fam Physician''. 1999;60(5):1443-1450.</ref>		*ESR >100 mm/hr has a ~90% probability of an identifiable underlying cause (most commonly infection, collagen vascular disease, or malignancy)<ref name="AAFP">Brigden ML. Clinical utility of the erythrocyte sedimentation rate. ''Am Fam Physician''. 1999;60(5):1443-1450.</ref>

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	==Clinical Features==		==Clinical Features==
	ESR is not ordered based on specific clinical features of the ESR itself — rather it is ordered as an ~~'''~~adjunct~~'''~~ to the clinical evaluation of underlying disease. Consider ESR in the following ED presentations:		ESR is not ordered based on specific clinical features of the ESR itself — rather it is ordered as an adjunct to the clinical evaluation of underlying disease. Consider ESR in the following ED presentations:

	*New headache in a patient >50 years — [[temporal arteritis]] evaluation		*New headache in a patient >50 years — [[temporal arteritis]] evaluation
Line 54:		Line 54:
	==Evaluation==		==Evaluation==
	===Workup===		===Workup===
	*ESR is a ~~'''~~venous blood test~~'''~~ — no special patient preparation required		*ESR is a venous blood test — no special patient preparation required
	*Order alongside ~~'''~~CRP~~'''~~ for improved diagnostic utility — CRP rises/falls faster and is more specific for acute inflammation<ref name="emDocs">Erythrocyte Sedimentation Rate and C-Reactive Protein in the ED. ''emDocs''. December 2023.</ref>		*Order alongside CRP for improved diagnostic utility — CRP rises/falls faster and is more specific for acute inflammation<ref name="emDocs">Erythrocyte Sedimentation Rate and C-Reactive Protein in the ED. ''emDocs''. December 2023.</ref>
	*'''Do not routinely order ESR''' in undifferentiated patients — it is nonspecific and false positives are distracting<ref name="emDocs"/>		*'''Do not routinely order ESR''' in undifferentiated patients — it is nonspecific and false positives are distracting<ref name="emDocs"/>
	*ESR turnaround is typically 1 hour (inherent to the test methodology), making it ~~'''~~slower than CRP~~'''~~ in most labs		*ESR turnaround is typically 1 hour (inherent to the test methodology), making it slower than CRP in most labs

	===Diagnosis===		===Diagnosis===
	ESR does not diagnose any specific disease. Interpret in context:		ESR does not diagnose any specific disease. Interpret in context:

	~~'''~~Back pain (spinal epidural abscess / vertebral osteomyelitis):~~'''~~<ref name="emDocs"/>		Back pain (spinal epidural abscess / vertebral osteomyelitis):<ref name="emDocs"/>
	*ESR and CRP are elevated in 94–100% of spinal infections, often in the absence of leukocytosis		*ESR and CRP are elevated in 94–100% of spinal infections, often in the absence of leukocytosis
	*Consider further imaging (MRI) if ESR >20 mm/hr and CRP >1 mg/dL with concerning history		*Consider further imaging (MRI) if ESR >20 mm/hr and CRP >1 mg/dL with concerning history
Line 68:		Line 68:
	*Normal ESR does NOT rule out epidural abscess or osteomyelitis in high-risk patients — proceed to MRI if clinical suspicion is high		*Normal ESR does NOT rule out epidural abscess or osteomyelitis in high-risk patients — proceed to MRI if clinical suspicion is high

	~~'''~~Septic arthritis:~~'''~~<ref name="emDocs"/>		Septic arthritis:<ref name="emDocs"/>
	*ESR >15 mm/hr and CRP >2 mg/dL are >90% sensitive for septic arthritis		*ESR >15 mm/hr and CRP >2 mg/dL are >90% sensitive for septic arthritis
	*However, this is ~~'''~~not specific~~'''~~ — many inflammatory arthropathies cause similar elevations		*However, this is not specific — many inflammatory arthropathies cause similar elevations
	*ESR and CRP should not change the decision to perform [[arthrocentesis]] when septic arthritis is suspected		*ESR and CRP should not change the decision to perform [[arthrocentesis]] when septic arthritis is suspected

	~~'''~~Temporal arteritis (giant cell arteritis):~~'''~~		Temporal arteritis (giant cell arteritis):
	*ACR classification criteria include ESR ≥50 mm/hr		*ACR classification criteria include ESR ≥50 mm/hr
	*CRP may be ~~'''~~more sensitive~~'''~~ than ESR for biopsy-positive GCA<ref name="Kermani">Kermani TA, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. ''Semin Arthritis Rheum''. 2012;41(6):866-871.</ref>		*CRP may be more sensitive than ESR for biopsy-positive GCA<ref name="Kermani">Kermani TA, et al. Utility of erythrocyte sedimentation rate and C-reactive protein for the diagnosis of giant cell arteritis. ''Semin Arthritis Rheum''. 2012;41(6):866-871.</ref>
	*~10% of biopsy-proven GCA cases have normal ESR and CRP at diagnosis — a normal ESR does ~~'''~~NOT~~'''~~ exclude the diagnosis if clinical suspicion is high<ref name="Kermani"/>		*~10% of biopsy-proven GCA cases have normal ESR and CRP at diagnosis — a normal ESR does NOT exclude the diagnosis if clinical suspicion is high<ref name="Kermani"/>
	*Polycythemia and elevated hematocrit can falsely lower ESR in patients with GCA<ref name="NormalGCA">Ganiats TG, et al. Temporal arteritis with normal erythrocyte sedimentation rate. ''J Am Board Fam Pract''. 1991;4(2):119-122.</ref>		*Polycythemia and elevated hematocrit can falsely lower ESR in patients with GCA<ref name="NormalGCA">Ganiats TG, et al. Temporal arteritis with normal erythrocyte sedimentation rate. ''J Am Board Fam Pract''. 1991;4(2):119-122.</ref>

	~~'''~~Osteomyelitis:~~'''~~		Osteomyelitis:
	*ESR is elevated in >90% of cases of spondylodiscitis<ref name="APR">Becker KL, et al. Acute phase reactants in infections: evidence-based review and a guide for clinicians. ''Open Forum Infect Dis''. 2015;2(3):ofv098.</ref>		*ESR is elevated in >90% of cases of spondylodiscitis<ref name="APR">Becker KL, et al. Acute phase reactants in infections: evidence-based review and a guide for clinicians. ''Open Forum Infect Dis''. 2015;2(3):ofv098.</ref>
	*ESR remains elevated for weeks to months after treatment initiation (useful for monitoring but not for early treatment response — use CRP for that)		*ESR remains elevated for weeks to months after treatment initiation (useful for monitoring but not for early treatment response — use CRP for that)

	~~'''~~ESR >100 mm/hr:~~'''~~<ref name="AAFP"/>		ESR >100 mm/hr:<ref name="AAFP"/>
	*Strongly suggests serious underlying disease (~90% will have an identifiable cause)		*Strongly suggests serious underlying disease (~90% will have an identifiable cause)
	*Most common: Infection (including abscess, endocarditis, osteomyelitis), malignancy (especially myeloma, lymphoma), autoimmune disease (GCA, SLE)		*Most common: Infection (including abscess, endocarditis, osteomyelitis), malignancy (especially myeloma, lymphoma), autoimmune disease (GCA, SLE)

	==Management==		==Management==
	*ESR is a ~~'''~~diagnostic adjunct~~'''~~ — management is directed at the underlying condition identified		*ESR is a diagnostic adjunct — management is directed at the underlying condition identified
	*'''Do not treat an elevated ESR in isolation''' — pursue the clinical diagnosis		*'''Do not treat an elevated ESR in isolation''' — pursue the clinical diagnosis
	*'''Do not use a normal ESR to exclude dangerous diagnoses''' in high-risk patients — proceed with definitive workup (MRI, arthrocentesis, temporal artery biopsy) when clinical suspicion warrants		*'''Do not use a normal ESR to exclude dangerous diagnoses''' in high-risk patients — proceed with definitive workup (MRI, arthrocentesis, temporal artery biopsy) when clinical suspicion warrants
Line 95:		Line 95:
	==Disposition==		==Disposition==
	*Disposition depends on the underlying diagnosis, not the ESR value itself		*Disposition depends on the underlying diagnosis, not the ESR value itself
	*An incidentally elevated ESR in an otherwise well-appearing patient with a benign clinical picture does ~~'''~~not~~'''~~ require ED admission — arrange outpatient follow-up for repeat testing and further evaluation		*An incidentally elevated ESR in an otherwise well-appearing patient with a benign clinical picture does not require ED admission — arrange outpatient follow-up for repeat testing and further evaluation
	*ESR >100 mm/hr warrants an identifiable explanation before discharge, or close outpatient follow-up with primary care or appropriate specialist		*ESR >100 mm/hr warrants an identifiable explanation before discharge, or close outpatient follow-up with primary care or appropriate specialist