Amino Acids, Metabolic & Newborn Screening
Every amino acids, metabolic & newborn screening calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
33 calculators in this section
- Alanine Unit ConverterConvert alanine between mg/dL and µmol/L, with fasting reference intervals by age — and the pairing that gives the number its meaning, because alanine is one transamination away from pyruvate and is read beside the lactate.
- Ammonia Interpretation CalculatorGrade plasma ammonia by age group and severity, and see why sampling technique matters as much as the number itself.
- Anion Gap Acidosis Cause IdentifierScreen a raised anion gap against lactate, ketones and the osmolal gap to narrow the cause using the GOLDMARK framework.
- Arginine Unit ConverterConvert arginine between mg/dL and µmol/L — and read the direction, because arginine is low in most urea cycle disorders and high in arginase deficiency, and it falls faster than any other amino acid in a sample left to stand.
- Asparagine Unit ConverterConvert asparagine between mg/dL and µmol/L, with fasting reference intervals by age — the amide partner of aspartic acid, deliberately emptied from plasma by asparaginase, and low in only about half of children with asparagine synthetase deficiency.
- Aspartic Acid Unit ConverterConvert aspartic acid — aspartate — between mg/dL and µmol/L, with fasting reference intervals by age, and see why one laboratory publishes an upper limit only for an amino acid that plasma holds barely any of.
- Cysteine Unit ConverterConvert cysteine between mg/dL and µmol/L — and check first which cysteine you have, because a plasma amino acid profile reports cystine, the oxidised dimer, and total cysteine after reduction is a third quantity again.
- Cystine Unit ConverterConvert cystine between mg/dL and µmol/L, with fasting reference intervals by age — and note that two large laboratories publish adult ceilings five times apart, because how long the sample stood decides how much cysteine has become cystine.
- Fischer Ratio CalculatorCalculate the Fischer ratio of branched-chain to aromatic amino acids, used to assess hepatic encephalopathy risk and nutritional status in liver failure.
- Galactose Unit ConverterConvert galactose between mg/dL and mmol/L — the same factor as glucose, because the two share a molecular mass — with the newborn screening cut-offs and why an abnormal screen is acted on before it is confirmed.
- Glutamic Acid Unit ConverterConvert glutamic acid — glutamate — between mg/dL and µmol/L, with fasting reference intervals by age, and see why a raised plasma glutamate is far more often a haemolysed or slowly separated sample than a finding.
- Glutamine Unit ConverterConvert glutamine between mg/dL and µmol/L, with the 1,000 µmol/L ceiling from the urea cycle guidelines — because glutamine is where waste nitrogen is stored, and it can still be raised after the ammonia has come back down.
- Glycine Unit ConverterConvert glycine between mg/dL and µmol/L — and see why the plasma level is not the diagnostic measure in non-ketotic hyperglycinaemia, where the CSF to plasma glycine ratio is, and why valproate has to be excluded first.
- Homocysteine Unit ConverterConvert homocysteine between mg/L, µg/mL and µmol/L, and see why a raised result points more often to B12 status than to cardiovascular risk.
- Isoleucine Unit ConverterConvert isoleucine between mg/dL and µmol/L, with fasting reference intervals by age — and note that the factor is identical to leucine's, because the two are isomers of the same mass, while the analytes are not interchangeable at all.
- Ketone Body Ratio Calculatorβ-hydroxybutyrate divided by acetoacetate — about 1:1 in health and up to 10:1 in ketoacidosis. The routine nitroprusside ketone test cannot see β-hydroxybutyrate at all, so it under-reads on arrival and can rise while the patient improves.
- Lactate to Pyruvate Ratio CalculatorLactate in mmol/L, pyruvate in µmol/L, handled explicitly. A raised lactate with a raised ratio points to the respiratory chain or to hypoxia; a raised lactate with a normal ratio points to pyruvate dehydrogenase deficiency — and the sample is easy to ruin before it reaches the laboratory.
- Leucine Unit ConverterConvert leucine between mg/dL and µmol/L, with the maple syrup urine disease treatment target — and why a rising leucine in MSUD is a neurological emergency rather than a number to repeat tomorrow.
- Lysine Unit ConverterConvert lysine between mg/dL and µmol/L, with fasting reference intervals by age — and why a low or even normal plasma lysine can be the more important result, because lysinuric protein intolerance presents with hyperammonaemia after protein.
- Methionine Unit ConverterConvert methionine between mg/dL and µmol/L — and see why the direction matters more than the size, since a raised homocysteine with a high methionine and one with a low methionine are two different disorders with two different treatments.
- Methylmalonic Acid (MMA) Unit ConverterConvert methylmalonic acid between µmol/L and nmol/L — the single most useful confirmatory test for functional B12 deficiency.
- N1-Methylnicotinamide Unit ConverterConvert N1-methylnicotinamide between mg/L, µg/L and µmol/L. This page converts at the mass of the CATION, 137.162 — not the chloride salt at 172.61 that most reference standards are supplied as, because using the salt's mass understates a molar result by about 21%.
- Ornithine Unit ConverterConvert ornithine between mg/dL and µmol/L, with fasting reference intervals by age — a urea cycle intermediate rather than a protein amino acid, where a raised result is read with the ammonia beside it.
- Phenylalanine to Tyrosine Ratio CalculatorCalculate the phenylalanine to tyrosine ratio used to confirm phenylketonuria on newborn screening, and see when a raised phenylalanine is something else entirely.
- Phenylalanine Unit ConverterConvert phenylalanine between mg/dL and µmol/L, and read the answer against the right figure — because the PKU treatment target sits above the untreated reference interval, and Europe and the ACMG no longer agree on where it ends.
- Proline Unit ConverterConvert proline between mg/dL and µmol/L, with fasting reference intervals by age — plus hyperprolinaemia types I and II, the vitamin B6 problem that type II creates, and why a haemolysed or slowly separated sample is the commonest reason a proline looks high.
- Pyrrolysine Unit ConverterConvert pyrrolysine between mg/dL and µmol/L at 255.318 Da. Read the next sentence before you use it: pyrrolysine does not occur in human protein and no clinical laboratory measures it, so this is arithmetic for a biochemistry audience and not a laboratory tool.
- Selenocysteine Unit ConverterConvert selenocysteine between mg/dL and µmol/L at 168.065 Da. The point of the page: free selenocysteine is not what anybody measures for selenium status. That is plasma or serum selenium, or selenoprotein P, and treating the three as one number is a real and repeated error.
- Serine Unit ConverterConvert serine between mg/dL and µmol/L, with fasting reference intervals by age — and why the CSF serine matters more than the plasma one, because in a serine biosynthesis defect a non-fasting plasma sample can be entirely normal.
- Threonine Unit ConverterConvert threonine between mg/dL and µmol/L, with fasting reference intervals by age — and see why threonine is one of the amino acids read as part of a whole profile rather than alone, starting with two published adult intervals that disagree by more than a hundred µmol/L.
- Tryptophan Unit ConverterConvert tryptophan between mg/dL and µmol/L, with fasting reference intervals by age — and the two pathways that give the number its meaning, because tryptophan is the precursor of both serotonin and niacin.
- Tyrosine Unit ConverterConvert tyrosine between mg/dL and µmol/L, with the age-dependent reference intervals — and why tyrosine is the wrong analyte to screen for tyrosinaemia type I with.
- Valine Unit ConverterConvert valine between mg/dL and µmol/L — with its own factor, not leucine's — and see why valine rises with leucine in maple syrup urine disease but is not the amino acid watched for decompensation, and is more often supplemented than restricted.