Systemic infections affecting the liver. Some cause jaundice, some do not

The patient who has clinical jaundice, abnormal results on liver function tests, or both presents a difficult diagnostic challenge. Many infectious diseases affect the liver, and the extent of involvement determines the degree of clinically apparent jaundice. Some diseases that affect the liver minimally cause no jaundice at all. An important clue to the cause of the disorder is the pattern of abnormal results on liver function tests. Increased alkaline phosphatase predominates with Q fever, secondary or tertiary syphilis, clonorchiasis, and hepatic candidiasis, while elevated levels of serum transaminases characterize viral hepatitis, leptospirosis, mononucleosis syndromes, legionnaires' disease, typhoid fever, toxic shock syndrome, and yellow fever. Increases in serum bilirubin are typical with jaundice caused by clostridial myelonecrosis, severe bacterial sepsis, and relapsing fever (borreliosis). These findings together with the patient's history, physical findings, and basic laboratory tests provide a presumptive diagnosis in most cases.