Unit Converter
Valine (Val)
(Essential Branched-Chain Amino Acid - Key for Muscle Metabolism, Nitrogen Balance & Energy Production)
Synonyms
- L-Valine
- Val
- Branched-chain amino acid (BCAA)
- 2-Amino-3-methylbutanoic acid
- Essential amino acid
Units of Measurement
- µmol/L
- mg/L
- mg/dL
- mg/100 mL
- mg%
- µg/mL
Unit Conversions
Molecular Weight of Valine = 117.15 g/mol
µmol/L → mg/L
1 µmol/L=0.117 mg/L1\ \text{µmol/L} = 0.117\ \text{mg/L}1 µmol/L=0.117 mg/L 1 mg/L=8.54 µmol/L1\ \text{mg/L} = 8.54\ \text{µmol/L}1 mg/L=8.54 µmol/L
mg/dL → mg/L
1 mg/dL=10 mg/L1\ \text{mg/dL} = 10\ \text{mg/L}1 mg/dL=10 mg/L
µg/mL → mg/L
1 µg/mL=1 mg/L1\ \text{µg/mL} = 1\ \text{mg/L}1 µg/mL=1 mg/L
mg/100 mL = mg% = mg/dL
Description
Valine is an essential branched-chain amino acid (BCAA) along with leucine and isoleucine.
It must be obtained through diet, especially from protein-rich foods.
Valine is crucial for:
- Muscle growth and repair
- Energy metabolism (BCAA oxidation)
- Nitrogen balance
- Glucose–alanine cycle
- Neurotransmitter modulation in the CNS
BCAAs bypass hepatic metabolism and are metabolized primarily in skeletal muscle, making valine a sensitive marker of muscle function and overall amino-acid status.
Physiological Role
1. Muscle Metabolism
Major energy source during exercise.
Essential for muscle repair and protein synthesis.
2. Glucose-Alanine Cycle
Transports nitrogen from muscle to liver for gluconeogenesis.
3. Nitrogen Metabolism
Valine is a key component of reversible transamination reactions.
4. CNS Neuroregulation
BCAAs compete with aromatic amino acids (Trp, Tyr) at the blood–brain barrier, influencing serotonin and dopamine balance.
Clinical Significance
ELEVATED VALINE
Less common in isolation.
1. Maple Syrup Urine Disease
BCAA accumulation (Val + Leu + Ile) due to branched-chain α-ketoacid dehydrogenase deficiency.
Clinical features:
- Sweet-smelling urine
- Lethargy, poor feeding
- Seizures
- Metabolic acidosis
- Elevated leucine is most toxic, but valine is also high.
2. High-Protein Intake
Dietary or supplement use (sports nutrition).
3. Catabolic Stress / Muscle Breakdown
- Trauma
- Burns
- Sepsis
- Chronic illness
4. Liver Disease
Impaired amino-acid homeostasis.
5. Hyperinsulinemia / Insulin Resistance
BCAAs (especially valine & leucine) elevated in metabolic syndrome.
LOW VALINE
1. Malnutrition / Protein Deficiency
2. Malabsorption
- Celiac disease
- Inflammatory bowel disease
- Pancreatic insufficiency
3. Liver Disease
Impaired transamination and BCAA metabolism.
4. MSUD During Treatment
Dietary restriction of BCAAs can lower valine excessively.
5. Chronic Illness
Low valine seen in chronic inflammation and cachexia.
Reference Intervals
(Tietz 8E + Mayo + ARUP - adults)
Plasma Valine
- 200 – 330 µmol/L
(= 23 – 39 mg/L)
Newborns / Infants
Slightly higher values are normal.
Diagnostic Uses
1. Screening for Maple Syrup Urine Disease (MSUD)
One of the three elevated BCAAs.
2. Monitoring BCAA Therapy
Used in patients on specialized amino-acid formulas.
3. Nutritional Assessment
Reflects protein sufficiency.
4. Metabolic & Liver Disease Evaluation
BCAA profile altered in cirrhosis.
5. Muscle Metabolism & Catabolism Monitoring
Valine rises with muscle breakdown.
6. ICU / Critical-Care Monitoring
Marker of metabolic stress.
Analytical Notes
- Fasting sample preferable (diet strongly affects levels).
- Plasma should be deproteinized promptly to prevent degradation.
- LC-MS/MS or HPLC used in newborn screening & metabolic labs.
- Hemolysis may contaminate sample with intracellular amino acids.
Clinical Pearls
- Elevated valine alone is rare - usually accompanies high leucine & isoleucine.
- In MSUD, leucine is the neurotoxic driver, but valine must also be monitored.
- Valine competes with tryptophan transport at BBB → may influence serotonin-related symptoms.
- Chronic liver disease alters BCAA/aromatic amino acid ratio - often low BCAA & high aromatic amino acids.
- Athletes consuming BCAA supplements may show mildly elevated valine levels.
Interesting Fact
Valine was first isolated from casein in milk - same as leucine - and its name derives from “valeric acid” due to structural similarity.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Amino Acids
- ACMG Guidelines - Maple Syrup Urine Disease
- Mayo Clinic Laboratories - Amino Acid Profile
- ARUP Consult - Metabolic Disorders
- Rosenberg et al. - Inborn Errors of Amino Acid Metabolism
- MedlinePlus (NIH) - Amino Acid Tests