Normal Total Bilirubin in a 61-Year-Old Patient

Case Report: Normal Total Bilirubin in a 61-Year-Old Patient – TB 0.5 mg/dL on Presentation

Introduction

Total bilirubin (TB) is an important marker in liver function tests that expresses the equilibrium between bilirubin synthesis, hepatic uptake, conjugation, and excretion. A normal TB suggests bilirubin metabolism is normal, which can be a valuable hint in assessing patients with systemic disease.

This case presentation reports a 61-year-old African-American man with several systemic symptoms and laboratory abnormalities but a normal total bilirubin (0.5 mg/dL). Interpreting this result in the context of other labs and clinical findings enables clinicians to develop a more informed understanding of liver involvement, progression of systemic disease, and prognosis.

Patient Profile

• Age: 61 years
• Ethnicity: African-American
• Gender: Male
• Relevant Medical History: Hypertension, mild diabetes
• Presenting Symptoms: Leg swelling, abdominal distension, fatigue, shortness of breath

Clinical Presentation

The patient history revealed:

• Leg swelling (edema) bilaterally over a period of 2–3 months
• Abdominal distension (ascites) with pain and early satiety
• Fatigue and weakness
• Mild shortness of breath on exertion
• Weight loss

Physical Examination Findings:

• Bilateral pitting lower extremity edema
• Tense ascites with positive fluid thrill
• Jugular venous distention (JVD)
• Mild hepatomegaly
• No jaundice, scleral icterus, or other acute liver failure signs

Laboratory Findings

• Total Bilirubin (TB): 0.5 mg/dL (normal: 0.2–1.2 mg/dL)
• Serum Albumin: 2.1 g/dL (hypoalbuminemia)
• Alkaline Phosphatase (AP): 718 IU/L
• AST: 158 IU/L
• ALT: 119 IU/L
• Renal Function: Increased creatinine, proteinuria
• Serum Protein Electrophoresis: Monoclonal light chain spike

Understanding Normal Total Bilirubin

Bilirubin metabolism:

1. Production: Bilirubin is produced from heme degradation in red blood cells.
2. Transport: Bilirubin is bound to albumin for transport to the liver.
3. Hepatic Conjugation: Conjugation in hepatocytes by UDP-glucuronyl transferase.
4. Excretion: Excreted in bile into the intestines.

Clinical implications of normal TB (0.5 mg/dL):

• Reflects effective hepatic uptake, conjugation, and biliary excretion.
• Implicates no acute hepatocellular injury leading to bilirubin accumulation.
• In the company of other abnormal liver enzyme (e.g., elevated AP, AST, ALT), normal TB may signify:
• Mild or early hepatic involvement
• Predominantly infiltrative or cholestatic pattern without bilirubin retention
• Normal bilirubin metabolism in spite of systemic illness

Differential Diagnosis and Interpretation

Though bilirubin is normal, the patient otherwise had significant findings:

1. Hepatic Amyloidosis:

• Deposition of amyloid can cause elevation of AP and a moderate increase in AST/ALT, but bilirubin is usually normal in early conditions.

1. Chronic Liver Disease:

• Infiltration or early fibrosis can result in elevation of enzymes without hyperbilirubinemia.

1. Systemic Infiltrative Disorders:

• Involvement of kidney and heart (amyloidosis) can suppress normal liver lab findings.

1. Other Causes of Edema and Ascites:

• Nephrotic syndrome, heart failure, or hypoalbuminemia can produce ascites without influencing bilirubin.

Diagnostic Workup

• Ultrasound Abdomen: Hepatomegaly, moderate ascites, no biliary obstruction
• Echocardiography: Restrictive cardiomyopathy
• Fat Pad Biopsy: Congo red positive, systemic amyloidosis confirmed
• Bone Marrow Biopsy: Plasma cell dyscrasia consistent with AL amyloidosis
• LFT Trend: TB remained normal; elevated AP, AST, ALT

Clinical Significance of Normal TB in Systemic Disease

• Prognostic Insight: Normal bilirubin implies liver synthetic function is basically intact.
• Diagnostic Clues: Differentiates early cholestatic or obstructive liver failure from infiltrative hepatic disease.
• Treatment Implications: Normal bilirubin permits more vigorous therapy since the liver is capable of metabolizing drugs normally.
• Monitoring: Trend TB in association with AP, AST, ALT to identify progression or increasing hepatic involvement.

Management

Supportive Care

• Diuretics for edema and ascites
• Low-salt diet to control fluid retention
• Nutritional management of hypoalbuminemia

Disease-Specific Therapy

• CyBorD regimen (Bortezomib + Cyclophosphamide + Dexamethasone)
• Stem Cell Transplant for selected patients
• Newer therapies such as Daratumumab in refractory disease

Monitoring

• Liver function tests such as TB, AP, AST, ALT
• Albumin and renal function tests
• Cardiac monitoring for restrictive cardiomyopathy
• Periodic clinical assessment of edema and ascites

Patient Outcome

• At 6 months of treatment:
• Edema and ascites were significantly improved
• Albumin rose slightly
• Liver enzymes improved, TB was normal
• Cardiac symptoms steadied
• Patient indicated better quality of life

Clinical Insights

For Clinicians

• Mildly normal TB does not exclude liver disease in systemic illness.
• Hepatic amyloidosis early in the course tends to raise AP but not bilirubin.
• Trend all LFTs longitudinally instead of focusing on one marker.

For Patients & Caregivers

• Normal bilirubin is comforting but does not necessarily imply liver is normal.
• Regular monitoring is crucial in multi-system illnesses such as amyloidosis.
• Early treatment enhances outcome and quality of life.

Wider Implications

This case highlights that normal laboratory results are misleading if taken out of context. In systemic illnesses such as amyloidosis:

• Normal bilirubin levels can exist with extensive hepatic infiltration.
• Evaluation of multiple organs is imperative.
• Combine laboratory results, imaging, and biopsy findings for diagnosis.

Conclusion

The presentation of a 61-year-old African-American male with normal total bilirubin (0.5 mg/dL) illustrates the need for thorough evaluation in systemic disease.

Although bilirubin was normal, other indicators showed evidence of liver involvement and systemic amyloidosis. This illustrates that normal lab results do not rule out serious pathology, and long-term monitoring, targeted treatment, and multidisciplinary management are necessary.