Biofluids in hypobaric hypoxia: best possible use, investigative strategies and putative markers

Hypobaric hypoxia (HH) is the hypoxia caused by decreased ambient atmospheric pressure (partial pressure of oxygen) as one ascends beyond 2500 m. The entire spectrum of molecular and biochemical studies regarding the effects of HH on an organism heavily depends on biological fluids during exposure to HH. The biological fluids are important sample types. This is because they are easiest to collect using minimally invasive collection procedures, easy to handle and store and low quantities are required for tests/assays. Although many reviews on hypobaric hypoxia in the recent past have been dedicated to the various advances made possible due to the study of biological fluids, biological fluids themselves have never been categorized according to studies done using them. This review concisely outlines the myriad results (particularly translational) in context of hypobaric hypoxia that have been observed in biological fluids, their collection strategies, storage strategies and ethical guidelines. Biological fluidscategorized here are blood (plasma and serum), saliva, tears and urine in context of research on HH and diseases like cancer where hypoxia is an essential condition. This review shall be of help to young investigators for choice of biological samples to be used in their experiments concerning hypoxia related studies and to clinicians involved in translational research providing them a ready reckoner for improving or modifying their approaches.