Unit Converter
alpha-1‑microglobulin
Synonym:
Alpha 1-microglobulin (A1M) , α1-microglobulin, Protein HC
Units of measurement
µmol/L, nmol/L, mg/L, mg/dL, mg/100mL, mg%, µg/mL
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ALPHA-1-MICROGLOBULIN (A1M)
(Low Molecular Weight Protein – Tubular Injury Marker)
Synonyms
- Alpha-1-Microglobulin
- A1M
- Protein HC
- α1-microglobulin
- Urinary A1M
- Low-molecular-weight glycoprotein
- HC protein
Units of Measurement
µmol/L, nmol/L, mg/L, mg/dL, mg/100mL, mg%, µg/mL
Description
Alpha-1-Microglobulin (A1M) is a low molecular weight (~26–33 kDa) glycoprotein synthesized primarily in the liver. It is freely filtered by the glomerulus and almost completely reabsorbed by proximal tubular cells.
Because of these properties, A1M is a sensitive marker of:
- Proximal tubular dysfunction / injury
- Tubulointerstitial nephritis
- Heavy metal nephrotoxicity
- Drug-induced kidney injury
- Early diabetic kidney damage (tubular phase)
A1M is measured both in serum and urine, with urine levels being more clinically useful.
Physiological Role
1. Immune modulation
A1M binds heme groups and protects tissues from oxidative damage.
2. Antioxidant function
Neutralizes free radicals, protects nephron structures.
3. Transport protein
Transports small molecules and peptides.
4. Kidney function biomarker
Reflects tubular integrity better than albumin in some conditions.
Clinical Significance
Elevated Urinary A1M
Major indicator of proximal tubular injury:
1. Tubulointerstitial Nephritis
- Acute & chronic forms
- Autoimmune causes
- Drug-induced interstitial nephritis (NSAIDs, PPIs, antibiotics)
2. Diabetic Kidney Disease (tubular phase)
Occurs earlier than albuminuria.
3. Toxic Nephropathies
- Heavy metals (cadmium, mercury, lead)
- Organic solvents
- Chemotherapy (cisplatin)
4. Other Renal Causes
- Acute tubular necrosis (ATN)
- Reflux nephropathy
- Polycystic kidney disease
- Viral nephritis
Elevated Serum A1M
Seen in:
- Chronic kidney disease (CKD)
- Decreased glomerular filtration
- Reduced tubular reabsorption
- Liver disease (increased production)
- Inflammatory states
Low A1M
Not typically clinically significant; may occur in:
- Severe hepatic failure (↓ synthesis)
- Protein-energy malnutrition
Reference Intervals
(Tietz 8E + Mayo + ARUP + IFCC ranges)
Serum Alpha-1-Microglobulin
- 10 – 30 mg/L
- Approx. 0.3 – 1.0 µmol/L
Urine Alpha-1-Microglobulin
- < 12 mg/L (spot urine)
- < 10 mg/g creatinine (normalized)
Elevated levels
- > 15 mg/L suggests tubular damage
- > 30 mg/L strongly indicates proximal tubular dysfunction
Units Description & Conversion Factors
Molecular Weight (approx.) = 26,000–33,000 g/mol
(Use average 30,000 g/mol for conversions)
Unit Meanings
| Unit | Meaning |
| µmol/L | micromole per liter |
| nmol/L | nanomole per liter |
| mg/L | milligram per liter |
| mg/dL | milligram per deciliter |
| mg/100mL | equivalent to mg% |
| mg% | milligrams per 100 mL |
| µg/mL | micrograms per milliliter |
Conversions
mg/L → µmol/L
µmol/L=mg/L30\text{µmol/L} = \frac{\text{mg/L}}{30}µmol/L=30mg/L
µmol/L → mg/L
mg/L=µmol/L×30\text{mg/L} = \text{µmol/L} \times 30mg/L=µmol/L×30
mg/dL → mg/L
mg/L=mg/dL×10\text{mg/L} = \text{mg/dL} \times 10mg/L=mg/dL×10
µg/mL → mg/L
mg/L=µg/mL×1\text{mg/L} = \text{µg/mL} \times 1mg/L=µg/mL×1
mg% = mg/dL
\text{mg/100 mL} = \text{mg%} = \text{mg/dL}
nmol/L → µmol/L
µmol/L=nmol/L÷1000\text{µmol/L} = \text{nmol/L} \div 1000µmol/L=nmol/L÷1000
Diagnostic Applications
1. Tubular Proteinuria Marker
A1M is a low-molecular-weight protein, so increased urinary A1M indicates tubular, not glomerular, pathology.
2. Occupational Medicine
Key biomarker for exposure to:
- Cadmium
- Mercury
- Lead
3. Early Diabetic Nephropathy
Detects tubular injury before albuminuria rises.
4. Monitoring Nephrotoxic Drugs
A1M rises early with toxicity from:
- Cisplatin
- Aminoglycosides
- Amphotericin B
5. Differentiating Proteinuria Types
- Albumin ↑, A1M normal → glomerular proteinuria
- A1M ↑, albumin normal → tubular proteinuria
- Both ↑ → mixed renal disease
Analytical Notes
- Measured using immunonephelometry or immunoturbidimetry.
- Urine A1M is more sensitive for tubular injury than serum.
- Minimal interference from hemolysis.
- Normalize urine values with urine creatinine for accuracy.
- Urinary A1M increases earlier than microalbumin in diabetic nephropathy.
- Very high levels (>50–100 mg/L) suggest severe tubular necrosis.
- Normal A1M + high albumin → glomerular injury (e.g., minimal change disease).
- A1M is more specific than β2-microglobulin because it is more stable in urine.
- Helpful in detecting kidney injury in toxic industrial exposures.
Interesting Fact
Alpha-1-Microglobulin is unique because it is both an acute-phase protein and a tubular injury marker, making it useful in both nephrology and clinical chemistry.
SEO Unit Converter Text
Alpha-1-Microglobulin (A1M) unit converter. Convert A1M values between mg/L, mg/dL, µmol/L, nmol/L, mg%, and µg/mL using accurate molecular-weight conversions. Includes normal urine and serum reference ranges and tubular injury interpretation.
References
- Tietz Clinical Chemistry and Molecular Diagnostics, 8th Edition — Plasma Proteins & Renal Markers.
- Mayo Clinic Laboratories — Alpha-1-Microglobulin, Serum/Urine.
- ARUP Consult — Proteinuria & Renal Tubular Marker Interpretation.
- IFCC – Guidelines for Protein Measurement.
- NIH / MedlinePlus — Urine Protein Markers.
- KDIGO – CKD & Tubular Injury Marker Reports.
- Occupational Toxicology Literature — Heavy Metal Exposure Biomarkers.