A1 alkaline phosphatase (ALP) level of 420 U/L with normal bilirubin suggests?

A1 alkaline phosphatase (ALP) level of 420 U/L with normal bilirubin suggests?

• A. Obstructive/cholestatic process or increased bone turnover
• B. Acute hepatitis
• C. Hemolysis
• D. Renal failure

Answer: (C)

Alkaline phosphatase comes from two main sources: liver/bile ducts and bone. When ALP is elevated but bilirubin remains normal, the clue points more toward bone turnover rather than a hepatobiliary (liver/bile) problem. In cholestasis or obstructive liver disease, bilirubin tends to rise because bile flow is impaired. So an ALP of 420 U/L with normal bilirubin most likely reflects increased bone turnover—such as from a healing fracture, Paget disease, or other metabolic bone conditions. To confirm the source, you’d look at an ALP isoenzyme or a GGT level: GGT rises with liver/bile sources but stays normal with bone sources. The other scenarios would usually present with different patterns: acute hepatitis typically raises bilirubin and liver enzymes; hemolysis elevates indirect bilirubin and LDH; renal failure doesn’t typically cause a marked ALP rise.

Alkaline phosphatase comes from two main sources: liver/bile ducts and bone. When ALP is elevated but bilirubin remains normal, the clue points more toward bone turnover rather than a hepatobiliary (liver/bile) problem. In cholestasis or obstructive liver disease, bilirubin tends to rise because bile flow is impaired. So an ALP of 420 U/L with normal bilirubin most likely reflects increased bone turnover—such as from a healing fracture, Paget disease, or other metabolic bone conditions.

To confirm the source, you’d look at an ALP isoenzyme or a GGT level: GGT rises with liver/bile sources but stays normal with bone sources. The other scenarios would usually present with different patterns: acute hepatitis typically raises bilirubin and liver enzymes; hemolysis elevates indirect bilirubin and LDH; renal failure doesn’t typically cause a marked ALP rise.