Dengue fever laboratory tests: Difference between revisions

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VisualWikitext

Latest revision as of 21:16, 29 July 2020

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Alonso Alvarado, M.D. [2]

Overview

The earliest abnormality in the complete blood count is decreased white cell count (leukopenia), which usually occurs during the febrile phase and should alert the physician to a high probability of dengue. The platelet count usually begins to drop when the temperature is returning to normal and is followed by findings indicative of plasma leakage such as elevated hematocrit level and hypoproteinemia. However, the extent of hemoconcentration may be affected by dilutional effect from excessive fluid administration or significant hemorrhage from the gastrointestinal tract and the white cell count may increase as a result of stress response. Serology and virology tests are used to confirm the diagnosis of dengue virus infection.

Laboratory Findings

Adapted from *Dengue: guidelines for diagnosis, treatment, prevention and control*. © World Health Organization 2009^[1]

Complete Blood Count

Progressive leukopenia (≤5000 cells/mm³) is the earliest laboratory abnormality in dengue virus infeciton. It is usually followed by an abrupt decline in the platelet count to about 100,000 cells/mm³ before the emergence of signs of plasma leakage.

Rising hematocrit concentrations may suggest impending hemorrhage. Plasma leakage is heralded by a rising hematocrit above the baseline value, and the extent of hemoconcentration reflects the severity of plasma leakage. However, this may be obscured by excessive intravenous fluid administration or significant hemorrhage from the gastrointestinal tract. Frequent hematocrit determinations are essential for guiding intravenous fluid therapy.

The hematocrit level normalizes or may be lower than the baseline due to the dilutional effect. The white cell count usually starts to rise soon after defervescence, while the recovery of the platelet count is typically delayed.

Metabolic Panel

Hypoproteinemia, accompanied by fluid accumulation such as pleural effusions or ascites, may be evident.

Metabolic acidosis, electrolyte disturbances, and abnormalities suggestive of organ dysfunction (including elevated aspartate transaminase, alanine transaminase, blood urea nitrogen, and creatinine) may occur as a result of tissue hypoperfusion associated with prolonged shock.

Laboratory Diagnostics

Virology and Serology Tests

Although the diagnosis is generally clinical in endemic areas, a diagnosis of confirmed dengue infection is definitively established by isolation of the virus, detection of viral genome or NS1 antigen, or seroconversion of IgM or IgG (from negative to positive IgM/IgG or fourfold increase in the specific antibody titer) in paired sera.

A positive IgM serology or a hemagglutination inhibition assay (HIA) antibody titer of 1280 or higher (or comparable figures by ELISA in a single specimen), are diagnostic of a probable dengue infection. Both probable and confirmed dengue cases should be notified to health authorities.^[2]

Definition	Method^†	Interpretation^†	Sample Characteristics
Confirmed Dengue Infection	Viral isolation	Virus isolated	Serum (collected at 1–5 days of fever) or necropsy tissues
	Genome detection	Positive RT-PCR or positive real-time RT-PCR
	Antigen detection	Positive NS1 Ag
	Antigen detection	Positive immunohistochemical	Necropsy tissues
	IgM seroconversion	From negative IgM to positive IgM in paired sera	Acute serum (days 1–5) and convalescent serum (15–21 days after first serum)
	IgG seroconversion	From negative IgG to positive IgG in paired sera or 4-fold increase IgG levels among paired sera
Probable Dengue Infection	Positive IgM	Positive IgM	Single serum collected after day 5
Probable Dengue Infection	High IgG levels	High IgG levels by ELISA or hemagglutination inhibition assay (≥1280)	Single serum collected after day 5

^† ELISA = enzyme-linked immunosorbent assay; IgG = immunoglobulin G; IgM = immunoglobulin M; NS1 Ag = non-structural protein 1 antigen; RT-PCR = reverse transcriptase polymerase chain reaction

Referemces

[WHO2009-1] "Dengue: guidelines for diagnosis, treatment, prevention and control" (PDF).

[WHO2012-2] "Handbook for Clinical Management of dengue" (PDF).

[1]

[2]

@@ Line 2: / Line 2: @@
 {{Dengue fever}}
-{{CMG}}
+{{CMG}}; {{AE}} {{Alonso}}
 ==Overview==
+The earliest abnormality in the [[complete blood count]] is decreased [[white cell]] count ([[leukopenia]]), which usually occurs during the febrile phase and should alert the physician to a high probability of dengue.  The [[platelet]] count usually begins to drop when the temperature is returning to normal and is followed by findings indicative of plasma leakage such as elevated [[hematocrit]] level and [[hypoproteinemia]]. However, the extent of [[hemoconcentration]] may be affected by dilutional effect from excessive fluid administration or significant [[hemorrhage]] from the [[gastrointestinal tract]] and the [[white cell]] count may increase as a result of [[stress response]]. [[Serology]] and [[virology]] tests are used to confirm the diagnosis of dengue virus infection.
-The earliest abnormality in the [[complete blood count]] is decreased [[white cell]] count, which usually occurs during the febrile phase. [[Leukopenia]] should alert the physician to a high probability of dengue. The [[platelet]] count usually begins to drop when the temperature is returning to normal and is followed by findings indicative of plasma leakage such as elevated [[hematocrit]] levels and [[hypoproteinemia]]. However, [[hemoconcentration]] may be abated by dilutional effects of excessive fluid administration and [[white cell]] count may increase as a result of [[stress response]]. [[Serology]] and [[virology]] tests are used to confirm the diagnosis of dengue virus infection.
+==Laboratory Findings==
+{| style="float: right; width: 350px;"
+| [[File:The course of dengue illness.png|400px|thumb|none|Adapted from ''Dengue: guidelines for diagnosis, treatment, prevention and control''. © World Health Organization 2009<ref name=WHO2009>{{cite web | title = Dengue: guidelines for diagnosis, treatment, prevention and control | url = http://whqlibdoc.who.int/publications/2009/9789241547871_eng.pdf?ua=1 }}</ref>]]
+|}
-==Laboratory Findings==
+===Complete Blood Count===
-===Electrolyte and Biomarker Studies===
+* Progressive [[leukopenia]] (≤5000 cells/mm<sup>3</sup>) is the earliest laboratory abnormality in dengue virus infeciton. It is usually followed by an abrupt decline in the [[platelet]] count to about 100,000 cells/mm<sup>3</sup> before the emergence of signs of plasma leakage.
-[[Serology]] and [[PCR]] (polymerase chain reaction) studies are available to confirm the diagnosis of dengue if clinically indicated.
+* Rising hematocrit concentrations may suggest impending hemorrhage. Plasma leakage is heralded by a rising [[hematocrit]] above the baseline value, and the extent of [[hemoconcentration]] reflects the severity of plasma leakage. However, this may be obscured by excessive [[intravenous therapy|intravenous fluid]] administration or significant [[hemorrhage]] from the [[gastrointestinal tract]]. Frequent [[hematocrit]] determinations are essential for guiding [[intravenous therapy|intravenous fluid therapy]].
-===Platelet Count===
+* The [[hematocrit]] level normalizes or may be lower than the baseline due to the dilutional effect.  The [[white cell]] count usually starts to rise soon after defervescence, while the recovery of the [[platelet]] count is typically delayed.
-The [[platelet]] count will drop until the patient's temperature is normal.
+===Metabolic Panel===
-===Hematocrit===
+* [[Hypoproteinemia]], accompanied by fluid accumulation such as [[pleural effusions]] or [[ascites]], may be evident.
-*In the presence of [[GI bleeding]], the [[hematocrit]] can drop.
+* [[Metabolic acidosis]], [[electrolyte]] disturbances, and abnormalities suggestive of organ dysfunction (including elevated [[aspartate transaminase]], [[alanine transaminase]], [[blood urea nitrogen]], and [[creatinine]]) may occur as a result of [[hypoperfusion|tissue hypoperfusion]] associated with prolonged [[shock]].
-*In the presence of severe [[dehydration]], the [[hematocrit]] may rise ([[hemoconcentration]]).
 ==Laboratory Diagnostics==
-=====Laboratory Method, Interpretation, and Sample Characteristics for Confirmed and Probable Dengue=====
+===Virology and Serology Tests===
+* Although the diagnosis is generally clinical in endemic areas, a diagnosis of '''confirmed dengue infection''' is ''definitively'' established by isolation of the [[virus]], detection of viral [[genome]] or NS1 [[antigen]], or [[seroconversion]] of [[IgM]] or [[IgG]] (from negative to positive [[IgM]]/[[IgG]] or fourfold increase in the specific [[antibody]] titer) in paired [[serum|sera]].
-A diagnosis of dengue virus infection is confirmed by the detection of the virus, the viral genome or NS1 antigen, or seroconversion of IgM or IgG (from negative to positive IgM/IgG or fourfold increase in the specific antibody titer) in paired sera.<ref name=WHO2012>{{cite web | title = Handbook for Clinical Management of dengue | url = http://apps.who.int/iris/bitstream/10665/76887/1/9789241504713_eng.pdf?ua=1 }}</ref>
+* A positive [[IgM]] [[serology]] or a [[hemagglutination inhibition assay|hemagglutination inhibition assay (HIA)]] [[antibody]] titer of 1280 or higher (or comparable figures by [[ELISA]] in a single specimen), are diagnostic of a '''probable dengue infection'''. Both probable and confirmed dengue cases should be notified to health authorities.<ref name=WHO2012>{{cite web | title = Handbook for Clinical Management of dengue | url = http://apps.who.int/iris/bitstream/10665/76887/1/9789241504713_eng.pdf?ua=1 }}</ref>
 {| style="border: 0px; font-size: 85%; margin: 3px;" align=center
 ! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Definition}}
-! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Method}}
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Method<sup>†</sup>}}
-! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Interpretation}}
+! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Interpretation<sup>†</sup>}}
 ! style="background: #4479BA; width: 100px;" | {{fontcolor|#FFF|Sample Characteristics}}
 |-
@@ Line 65: / Line 71: @@
 | style="padding: 5px 5px; background: #F5F5F5;" | High IgG levels by ELISA or hemagglutination inhibition assay (≥1280)
 |}
+&nbsp;&nbsp;<SMALL> <sup>†</sup> ELISA = enzyme-linked immunosorbent assay; IgG = immunoglobulin G; IgM = immunoglobulin M; NS1 Ag = non-structural protein 1 antigen; RT-PCR = reverse transcriptase polymerase chain reaction</SMALL>
 ==Referemces==
@@ Line 73: / Line 81: @@
 [[Category:Flaviviruses]]
 [[Category:Hemorrhagic fevers]]
-[[Category:Infectious disease]]
 [[Category:Insect-borne diseases]]
 [[Category:Neglected diseases]]
 [[Category:Tropical disease]]
 [[Category:Viral diseases]]
+[[Category:Emergency medicine]]
+[[Category:Disease]]
+[[Category:Up-To-Date]]
+[[Category:Infectious disease]]
+[[Category:Hematology]]
+[[Category:Cardiology]]
+[[Category:Gastroenterology]]