What are the differential diagnoses and management options for an 18-year-old patient with abdominal pain, previously showing mild transaminitis (elevated liver enzymes) and mildly elevated Thyroid-Stimulating Hormone (TSH) levels?

Differential Diagnoses for an 18-Year-Old with Abdominal Pain, Mild Transaminitis, and Elevated TSH

In an otherwise healthy 18-year-old with abdominal pain, mild transaminitis, and elevated TSH, the most likely diagnoses are biliary tract disease (particularly choledocholithiasis or cholecystitis), followed by autoimmune hepatitis, with hypothyroidism as a concurrent but likely unrelated finding. 1, 2

Immediate Diagnostic Approach

Critical Laboratory Tests to Order Now

• Repeat comprehensive metabolic panel with liver function tests (AST, ALT, alkaline phosphatase, total bilirubin) - the temporal relationship between pain onset and transaminase elevation is crucial, as levels correlate strongly with duration of symptoms in biliary disease 3
• Complete blood count with differential to assess for leukocytosis (>11,000/μL), which indicates infection or inflammation 1, 2
• Serum lipase (>3× upper limit of normal is diagnostic for pancreatitis) 1
• C-reactive protein as a sensitive marker for acute inflammation 1
• Beta-hCG in this female patient to absolutely rule out pregnancy-related conditions including ectopic pregnancy 1, 2

Key Clinical Details to Elicit

• Exact timing of pain onset relative to laboratory testing - transaminases increase progressively with pain duration in choledocholithiasis, with patients evaluated within 6 hours often showing normal or minimal LFT elevations that then increase 6.8-10.5 fold within 24 hours 3
• Character and location of pain - severe upper abdominal pain with markedly elevated transaminases strongly suggests biliary disease rather than primary hepatic disease 4
• Presence of jaundice, fever, or right upper quadrant tenderness 5
• Dietary history and recent weight loss - rapid weight loss increases cholelithiasis risk 5

Primary Differential Diagnoses

1. Biliary Tract Disease (Most Likely)

Choledocholithiasis or cholecystitis should be at the top of your differential because severe abdominal pain with elevated transaminases is more commonly associated with biliary disease than primary hepatic processes, even when transaminases are markedly elevated 4, 6

• Patients can present with a "hepatocellular pattern" (elevated ALT/AST) despite having isolated biliary disease with no hepatocellular injury 4
• ALT elevation ≥5× upper limit of normal is rare in other conditions and should prompt investigation for biliary pathology 5
• Immediate imaging: Right upper quadrant ultrasound is the initial test of choice with >90% sensitivity for gallbladder disease 1, 2
• If ultrasound is negative but clinical suspicion remains high, repeat LFTs within 24 hours - the absence of significant biochemical abnormalities within 24 hours makes symptomatic choledocholithiasis unlikely 3
• Concomitant elevation of ALT and alkaline phosphatase increases likelihood of biliary disease 5

2. Autoimmune Hepatitis (AIH)

Consider AIH given the age, sex (if female), and transaminitis pattern 5

• New or worsening symptoms like abdominal pain, severe fatigue, nausea, or vomiting should raise suspicion 5
• Additional testing needed: Autoimmune markers (ANA, anti-smooth muscle antibody, anti-LKM), immunoglobulin G levels 5
• Transaminase levels should be maintained below 3× upper limit of normal to reduce likelihood of aggressive interface hepatitis and disease progression 5
• May require liver biopsy if serologies are positive and imaging excludes biliary disease 5

3. Drug-Induced Liver Injury (DILI)

Obtain thorough medication history including over-the-counter drugs, herbal supplements, and dietary supplements 5

• ALT elevation ≥5× upper limit of normal that represents significant change from baseline should not be attributed to other causes without excluding DILI 5
• Concomitant elevation of ALT and alkaline phosphatase may indicate mixed hepatocellular-cholestatic DILI 5

4. Metabolic/Storage Disorders

Less likely but consider in young patients with hepatomegaly and unexplained transaminitis 5

• Glycogen storage diseases can present with hepatomegaly, elevated AST/ALT, and hypoglycemia 5
• Check fasting glucose and ketones if there are episodes of hypoglycemia 5

5. Infectious Causes

• Viral hepatitis serologies (hepatitis A, B, C, E) should be obtained 5
• Unusual infections like Enterobius vermicularis (pinworm) can rarely cause transaminitis and abdominal pain 7
• Consider stool studies if diarrhea is present 1

Regarding the Elevated TSH

The mildly elevated TSH is likely a separate issue from the acute abdominal pain and transaminitis and represents subclinical or overt hypothyroidism requiring separate evaluation and management. However, complete the acute abdominal workup first before addressing thyroid management.

Critical Pitfalls to Avoid

• Do not assume elevated transaminases always indicate primary hepatocellular disease - biliary obstruction can cause marked transaminase elevation (even >1000 IU/L) without hepatocellular injury 4, 6
• Do not delay imaging if initial LFTs are normal but biliary pain is suspected - repeat LFTs within 24 hours as they may dramatically increase 3
• Do not attribute ALT elevation ≥5× ULN to non-specific causes without thorough investigation for biliary disease, viral hepatitis, autoimmune hepatitis, or DILI 5
• Never proceed with imaging before obtaining beta-hCG in women of reproductive age 1, 2

Immediate Management Algorithm

1. Obtain beta-hCG immediately 1, 2
2. Order right upper quadrant ultrasound as first-line imaging 1, 2
3. Repeat comprehensive metabolic panel, CBC, CRP, lipase 1, 2
4. If ultrasound shows biliary pathology: Gastroenterology consultation for possible ERCP 4
5. If ultrasound is negative but pain persists: Repeat LFTs in 12-24 hours and consider CT abdomen with contrast 1, 3
6. If transaminases continue rising without biliary explanation: Add autoimmune workup and viral hepatitis serologies 5