What the values show

• Pattern: This is a mild mixed picture, with ALT, ALP and GGT all up and bilirubin normal. By my calculation the ALT/ALP ratio (R) is about 1.7, which leans slightly cholestatic. The liver is irritated, but synthetic function and bile excretion look preserved. I can't judge synthetic function fully without albumin and INR.
• CRP: After a month of fever and 10 days of antibiotics, 13.5 mg/L is low. That makes a large undrained abscess or severe bacterial sepsis less likely. It does not rule out partially treated enteric fever, TB, a viral illness or a non-infectious cause.

Likely causes in a 23-year-old with a month of fever

1. Enteric (typhoid) fever, partially treated. This is very common in South Asia. Fever lasts weeks and ALT is often raised more than AST. Antibiotics can blunt the culture result and the CRP.
2. Viral hepatitis (A, E, B) or an acute viral infection that also affects the liver. EBV or CMV mononucleosis is especially likely in a young adult. It causes prolonged fever, raised ALT, ALP and GGT, and often lymph node or spleen enlargement.
3. Tuberculosis. This includes miliary or hepatic TB, which often gives raised ALP and GGT with prolonged fever.
4. Brucellosis. Consider it with raw milk or animal exposure.
5. Malaria, leptospirosis, rickettsial infection. These depend on exposure.
6. Liver abscess, especially amoebic. Check for right upper quadrant pain.
7. Drug-induced liver injury. Antibiotics such as amoxicillin-clavulanate, macrolides and cephalosporins can cause this pattern. So can repeated or high-dose paracetamol taken for the fever. Review every medicine he has taken.
8. Early HIV infection, lymphoma, adult-onset Still's disease, inflammatory bowel disease. These are less common, but they are on the list if infections are excluded.

Tests that would narrow it down

• CBC with differential and a peripheral smear. Look for atypical lymphocytes (EBV), low platelets (dengue, malaria, typhoid), low counts, and a malaria parasite test.
• Blood cultures, even on antibiotics, plus a typhoid PCR or Typhidot test. Widal is unreliable.
• Viral hepatitis markers: HBsAg, anti-HCV, anti-HAV IgM and anti-HEV IgM. Also EBV and CMV serology, and HIV.
• Brucella serology, depending on exposure.
• ESR, ferritin and LDH. A very high ferritin points toward Still's disease, hemophagocytosis or lymphoma.
• Albumin and PT/INR, to check liver synthetic function.
• Chest X-ray and Mantoux or IGRA. Sputum or other TB workup if indicated.
• Ultrasound of the abdomen. It checks for liver or spleen enlargement, abscess, enlarged abdominal lymph nodes and gallbladder or bile duct problems. This is the most useful single next test.
• If everything stays unexplained, CT, or PET-CT, may be needed for a fever lasting this long. A recent meta-analysis of PET-CT in fever of unknown origin supports its role there.

Practical points

• A month of fever meets the usual time threshold for prolonged fever or fever of unknown origin. He needs a proper in-person workup rather than just another antibiotic course. Ideally he would be seen by a physician or infectious disease specialist.
• He should avoid alcohol and unnecessary medicines, and limit paracetamol, until the liver enzymes are explained.
• Do not start empirical TB treatment or steroids without a diagnosis. Both can hide the picture and harm the liver.
• See him urgently if he develops jaundice, dark urine, persistent vomiting, severe abdominal pain, confusion, bleeding, breathlessness or a very high fever.