D-arabinitol is a naturally occurring five-carbon sugar alcohol, also known as a polyol. This organic compound is found in biological systems.
Understanding D-Arabinitol’s Origins
The human body produces D-arabinitol through carbohydrate metabolism, specifically from D-arabinose via enzymes. Levels from this internal production are low.
D-arabinitol also originates from external sources, primarily from the metabolic activity of microorganisms. Fungi, especially Candida species, are known producers. Candida albicans, a common yeast, produces significant amounts in laboratory cultures and within infected hosts.
Other Candida species like C. tropicalis, C. parapsilosis, and C. pseudotropicalis also produce this sugar alcohol. However, some species, such as Candida krusei and Torulopsis glabrata, do not produce detectable levels. Fungi produce D-arabinitol as they metabolize carbohydrates.
Its Role as a Health Indicator
Elevated D-arabinitol levels serve as a diagnostic marker for certain types of fungal infections, particularly invasive candidiasis. This severe infection, caused by Candida species, can affect various body parts, including blood, heart, brain, and bones. Fungi produce D-arabinitol as a metabolite; during overgrowth or systemic infection, it accumulates and is excreted.
Elevated serum or urinary D-arabinitol levels correlate with systemic invasive candidiasis in immunocompromised individuals. This includes patients undergoing chemotherapy, transplant recipients, and those in intensive care units, who are at higher risk. Detecting D-arabinitol can aid diagnosis, sometimes days or weeks before traditional blood cultures yield positive results.
While heavily associated with Candida infections, elevated D-arabinitol is not exclusively specific to this condition. Other factors, such as dietary intake of pentose sugars or certain bacterial infections, can also influence D-arabinitol levels. Its measurement is therefore used in conjunction with other clinical findings and laboratory tests to establish a definitive diagnosis.
How D-Arabinitol Levels Are Assessed
D-arabinitol levels are typically assessed through laboratory tests, most commonly using urine or blood samples. Urine testing, often part of an Organic Acids Test (OAT), measures the levels of various metabolites, including D-arabinitol. Blood tests can also be performed, although urine is frequently chosen due to the higher concentration of D-arabinitol found in urine compared to serum.
The general process for a patient involves providing a urine sample, which is then analyzed using techniques such as gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography (HPLC). These methods are capable of accurately detecting even small increases in D-arabinitol levels. To account for variations in urine concentration, the D-arabinitol level is often reported as a ratio to creatinine, providing a normalized value for comparison.
Medical professionals, such as infectious disease specialists or those managing immunocompromised patients, might order this test. Elevated D-arabinitol levels typically suggest an active Candida infection or overgrowth. For instance, a reference value for D-arabinitol in urine is often considered to be less than or equal to 73 mcg/mg creatinine. However, results require interpretation by healthcare professionals, who consider them alongside a patient’s symptoms, medical history, and other diagnostic findings to form a comprehensive clinical picture.