Valerate, isovalerate and isobutyrate constitute the putrefactive short chain fatty acids (SCFAs). 

Valerate, isovalerate and isobutyrate are produced exclusively by fermentation of protein. These SCFAs are putrefactive, and suggest underlying protein maldigestion, malabsorption, or BOSI.

Pyridoxal 5'-Phosphate (PLP), also known as the active form of vitamin B6, is a versatile and essential coenzyme in various enzymatic reactions in the body, particularly in amino acid metabolism. Serving as a coenzyme for over 100 enzymes, PLP plays a pivotal role in biochemical processes including transamination, decarboxylation, and glycogen phosphorylase activity. Its transaminase activity is crucial for the synthesis and breakdown of amino acids, aiding in the interconversion between amino acids and alpha-keto acids.

A major metabolite of vitamin B6. High pyridoxic acid indicates high recent intake of vitamin B6. Because some individuals may require very high doses of vitamin B6, high values do not necessarily indicate the need to reduce vitamin B6 intake. Low values are associated with low B6 status, high oxalates, and/or low neurotransmitters.

The main urinary metabolite of pyridoxine (Vitamin B6) and is a measure of recent dietary intake.
Low values of pyridoxic acid in the urine indicate low recent intake while high values indicate high recent dietary intake.

- Pyridoxic acid (4-Pyridoxate) is a catabolic product of vitamin B6 that is excreted in the urine. Pyridoxic acid represents > 90% of vitamin B6 species excreted in the urine, and 40-60% of dietary vitamin B6 intake. Urine 4-pyridoxic acid correlated with plasma PLP and RBC PLP.

- 4-Pyridoxic acid level varies according to vitamin B6 intake and responds within 1–2 weeks to vitamin B6 depletion and repletion. Very low levels (<dl on the report) may indicate B6 need, and very high levels may identify excess intake.

- Increased xanthurenic acid after a tryptophan load may occur in vitamin B6-deficient individuals.

- In a mathematical model without a tryptophan load, xanthurenic acid and kynurenine increased at a more pronounced deficiency. Kynurenic acid may be more sensitive but may also result in a slight decrease.

Pyridoxic Acid (PA), often referred to as B6Pro, is a significant metabolite of Vitamin B6 that serves as a reliable biomarker for assessing vitamin B6 status in the body. Vitamin B6, a collective term for several related compounds including pyridoxal, pyridoxine, and pyridoxamine, is essential for numerous physiological functions, particularly those involved in amino acid metabolism, neurotransmitter synthesis, and hemoglobin formation. When Vitamin B6 is metabolized in the body, it is primarily converted into Pyridoxic Acid, which is then excreted in the urine.

A major metabolite of vitamin B6. High pyridoxic acid indicates high recent intake of vitamin B6. Because some individuals may require very high doses of vitamin B6, high values do not necessarily indicate the need to reduce vitamin B6 intake. Low values are associated with low B6 status, high oxalates, and/or low neurotransmitters.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate is a step in the production/recycling of glutathione. Glutathione is one of the most potent anti-oxidants in the human body. It is especially important in getting rid of toxins, including the harmful metabolites of estrogen detoxification 4-OH-E1 and 4-OH-E2.

In healthy individuals, a very modest amount of Pyroglutamate is spilled in the urine.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate is an intermediate in glutathione recycling and production. Glutathione requires the amino acids cysteine, glycine and glutamate for production. If the body cannot convert pyroglutamate forward to glutathione, it will show up elevated in the urine. High pyroglutamate is an established marker for glutathione deficiency. Remember that glutathione is one of the most potent antioxidants in the human body and is especially important in getting rid of toxins including the reactive quinone species formed by 4-OH-E1 and 4-OH-E2. This reactive species can damage DNA if not detoxified by either methylation or glutathione.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamate (or Pyroglutamic acid) is an intermediate in the glutathione metabolism and a marker of glutathione deficiency.

Pyroglutamic acid (5-oxoproline) is produced and utilized in the gamma-glutamyl cycle. This cycle is needed to assist in the production and recycling of glutathione (GSH), a powerful antioxidant.

Glutathione is a tripeptide, consisting of glutamate, cysteine, and glycine. Using the gamma-glutamyl cycle, GSH is divided into cysteinyl glycine and a gammaglutamyl molecule which attaches to another amino acid for transport across a membrane or into a cell. Gammaglutamyl transferase then splits off that attached amino acid, and the glutamate becomes pyroglutamic acid (5-oxoproline).

Cysteinyl glycine is also broken down and transported into the cell as cysteine and glycine. The entire GSH molecule needs to be reformed intracellularly from pyroglutamic acid by recombining cysteine, glycine, and glutamic acid using GSH synthetase.

This enzymatic reformation requires cofactors such as ATP and magnesium.