Is alkaline phosphatase (ALP) elevated in patients with HELLP (Hemolysis, Elevated Liver enzymes, and Low Platelet count) syndrome?

Alkaline Phosphatase in HELLP Syndrome

Alkaline phosphatase (ALP) is typically normal in HELLP syndrome, not elevated. This is an important distinguishing feature that can help differentiate HELLP from other hepatobiliary disorders.

Key Laboratory Findings in HELLP

The characteristic laboratory abnormalities in HELLP syndrome do not include elevated alkaline phosphatase:

• The most reliable laboratory tests for diagnosing HELLP are complete blood count with peripheral smear, lactate dehydrogenase (LDH), serum transaminases (AST/ALT), and urinalysis 1

• In documented HELLP cases, alkaline phosphatase remained within normal limits despite significant elevations in other liver enzymes 2

• The Tennessee Classification System defines HELLP by hemolysis with increased LDH (>600 U/L), AST (≥70 U/L), and platelets <100 x 10⁹/L—notably excluding ALP as a diagnostic criterion 3

Typical Liver Enzyme Pattern in HELLP

The hepatic injury pattern in HELLP differs from cholestatic liver disease:

• Transaminases (AST and ALT) are markedly elevated, with AST typically reaching 159-229 U/L or higher 2, 4

• LDH elevation is a hallmark feature, often exceeding 295-600 U/L, reflecting both hemolysis and hepatocellular injury 2, 1, 3

• Indirect hyperbilirubinemia may occur (2-8 mg/dL range) due to hemolysis, but direct bilirubin elevation is minimal 4

Clinical Significance

This normal ALP finding has important diagnostic implications:

• The absence of ALP elevation helps distinguish HELLP from cholestatic conditions like acute fatty liver of pregnancy, intrahepatic cholestasis of pregnancy, or biliary obstruction 5, 6

• The pathophysiology of HELLP involves periportal hepatocyte necrosis from placental Fas Ligand and reduced portal blood flow from thrombotic microangiopathy—not biliary obstruction or cholestasis, which would elevate ALP 7

• If ALP is significantly elevated in a patient with suspected HELLP, consider alternative or concurrent diagnoses such as choledocholithiasis, primary sclerosing cholangitis, or infiltrative liver disease 5, 6

Monitoring Recommendations

For confirmed HELLP syndrome:

• LDH and platelet count are the two best tests to monitor disease progression, not ALP 1

• Laboratory abnormalities typically resolve within 10 days following delivery, with the syndrome peaking at 24 hours postpartum 1, 4