Albumin - Increased and Decreased Conditions

INCREASED Albumin (Hyperalbuminemia)

True increases in albumin synthesis are rare. Hyperalbuminemia is almost always a concentration effect.

DECREASED Albumin (Hypoalbuminemia)

1. Decreased Synthesis (Liver)

• Liver cirrhosis / chronic liver disease - impaired hepatic synthesis
• Malnutrition / starvation / fasting - lack of amino acid substrate
• Malabsorption syndromes - reduced nutrient absorption
• Hepatic dysfunction of any cause

2. Increased Loss

• Nephrotic syndrome - urinary loss of albumin (proteinuria); albumin preferentially filtered due to small size
• Protein-losing enteropathy - GI loss of albumin
• Ascites - albumin leaks into ascitic fluid (especially in cirrhosis and portal hypertension)
• Burns / exudative wounds - skin loss

3. Increased Catabolism

• Acute severe infection / sepsis - reduced production + increased catabolism within 12-36 hours, nadir at ~5 days
• Inflammatory states - diversion of synthetic capacity to acute-phase proteins (CRP, fibrinogen, etc.)

4. Dilutional

• IV fluid administration (hospitalized patients)
• Pregnancy - physiological hemodilution

5. Chronic/Systemic Diseases

• Malignancy
• Congestive heart failure
• Inflammatory bowel disease
• Rheumatologic/autoimmune diseases
• Advancing age

Clinical Significance of Low Albumin

• Edema - loss of oncotic pressure causes fluid to leak into interstitial spaces
• Falsely low calcium/magnesium - because ~40-50% of calcium is albumin-bound; corrected calcium = measured Ca + 0.8 × (4 - serum albumin)
• Drug toxicity - drugs that are normally albumin-bound (warfarin, phenytoin) become more free/active
• Marker of prognosis - low albumin correlates strongly with mortality in hospitalized patients and cirrhosis
• SAAG (Serum-Ascites Albumin Gradient):
  • SAAG ≥ 1.1 g/dL → portal hypertension
  • SAAG < 1.1 g/dL → non-portal cause (malignancy, peritoneal TB, etc.)

Globulin - Increased and Decreased Conditions

INCREASED Globulin (Hyperglobulinemia)

α1-Globulin Increased

• Acute inflammation / acute-phase response (α1-antitrypsin is an acute-phase protein)
• Pregnancy
• Oral contraceptive use
• Malignancy

α1-Globulin Decreased

• α1-antitrypsin deficiency - major cause; leads to emphysema and liver disease
• Severe liver disease (reduced synthesis)
• Neonatal period (physiologically low)

α2-Globulin Increased

• Nephrotic syndrome - haptoglobin and α2-macroglobulin retained (α2-macroglobulin is too large to be lost in urine)
• Acute inflammation (haptoglobin, ceruloplasmin are acute-phase proteins)
• Hemolysis (haptoglobin initially rises then falls as it is consumed)
• Cushing's syndrome / steroid therapy
• Diabetes mellitus

α2-Globulin Decreased

• Hemolytic anemia (haptoglobin consumed by binding free hemoglobin)
• Severe liver disease
• Malnutrition

β-Globulin Increased

• Iron-deficiency anemia - transferrin rises as a compensatory response
• Hypothyroidism - elevated LDL
• Pregnancy - transferrin increases
• Obstructive jaundice (lipoprotein-X accumulation)
• Chronic liver disease (IgA migration into beta zone - "beta-gamma bridging" in cirrhosis)

β-Globulin Decreased

• Malnutrition
• Hepatocellular failure

γ-Globulin (Immunoglobulin) - INCREASED (Polyclonal)

• Chronic infections - tuberculosis, viral hepatitis, HIV, malaria, leprosy, infective endocarditis
• Autoimmune diseases - SLE, rheumatoid arthritis, Sjögren's syndrome, autoimmune hepatitis
• Liver cirrhosis - classically shows polyclonal gamma elevation + beta-gamma bridging on SPEP
• Sarcoidosis
• Granulomatous diseases
• Parasitic infections - kala-azar (very high IgG), malaria

γ-Globulin - INCREASED (Monoclonal - "M-spike")

• Multiple myeloma (plasma cell myeloma) - most common; usually IgG or IgA
• Waldenström's macroglobulinemia - IgM monoclonal
• Monoclonal Gammopathy of Undetermined Significance (MGUS) - benign but requires monitoring
• Primary amyloidosis (AL amyloidosis)
• Solitary plasmacytoma
• Chronic lymphocytic leukemia (CLL)

γ-Globulin DECREASED (Hypogammaglobulinemia)

• Primary immunodeficiency states:
  • X-linked agammaglobulinemia (Bruton's) - absent B cells, very low all Ig
  • Common variable immunodeficiency (CVID)
  • Selective IgA deficiency - most common primary immunodeficiency
• Secondary causes:
  • Nephrotic syndrome - immunoglobulins lost in urine
  • Protein-losing enteropathy
  • Multiple myeloma (paradoxically - normal Ig suppressed while monoclonal Ig rises)
  • Post-splenectomy
  • Immunosuppressive therapy - corticosteroids, chemotherapy
  • HIV/AIDS (late stage)
  • Malnutrition

A/G Ratio (Albumin/Globulin Ratio)

• Normal: 1.2 - 2.2
• Low A/G ratio (< 1): seen when globulins are elevated (myeloma, cirrhosis, autoimmune disease) or albumin is decreased
• High A/G ratio: seen in hypogammaglobulinemia or high albumin (rare)

Quick Summary Table

Albumin/Globulin (A/G) Ratio - Pathology

How it is Calculated

A/G Ratio = Albumin ÷ (Total Protein - Albumin)

• Globulin = Total Protein - Albumin
• Normal A/G ratio: 1.2 - 2.2 (albumin normally exceeds globulin)
• The ratio is clinically useful because it accentuates abnormalities - when albumin falls and globulins rise simultaneously, the numerator and denominator move in opposite directions, producing an exaggerated change.

DECREASED A/G Ratio (Reversed Ratio)

• Albumin decreases, or
• Globulins increase, or
• Both occur simultaneously (most common in disease)

Causes of Decreased/Reversed A/G Ratio

Key rule from Quick Compendium of Clinical Pathology: An A/G ratio < 1.0 is usually the result of liver disease. Any cause of impaired hepatic synthesis combined with enhanced immunoglobulin synthesis results in a decreased A/G ratio.

INCREASED A/G Ratio

Why the Ratio Matters Clinically