Table 2.

Important laboratory parameters and their significance in COVID-19

Parameter	Normal/threshold value	Pathological observations in COVID-19	Effect on disease progression	References
D-dimer	500 µg/L FEU (age-adjusted cutoffs recommended)	Marked increase	Increased risk of VTE Presence of low-grade DIC May be associated with severe COVID-19	[132]
aPTT	21–35 seconds	Mild prolongation		[135]
PT	11–12.5 seconds	Mild prolongation		[43]
Platelet count	150 x 109–450 × 109 cells/L	Mild decrease		[50,126]
Fibrinogen	200–400 mg/dL	At upper limits of normal		[43]
Lactate Dehydrogenase (LDH)	140–280 units/L	Increase	Thrombotic microangiopathy	[80,135]
Ferritin	Men: 24–336 µg/L Women: 11–307 µg/L	Striking increase
CRP	10–1000 mg/L	Increased	Marker of inflammation in severe COVID-19	[136,137]
PCT	0.15 ng/mL	Normal to slight increase	Presence of bacterial co-infection in severe COVID-19	[134]