Volume Regulation and Renal Function at High Altitude across Gender

Abstract

AimsWe investigated changes in volume regulating hormones and renal function at high altitudes and across gender.MethodologyIncluded in this study were 28 subjects (n = 20 males; n = 8 females. ages: 19 – 65 yrs), who ascended to a height of 3440m (HA1), on the 3rd day and to 5050m (HA2), on the 14th day. Plasma and urinary creatinine and urinary osmolality as well as plasma levels of plasma renin activity (PRA), Aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP) were measured. The plasma volume loss (PVL) was estimated from plasma density and hematocrit. Glomerular filtration rate (GFR) was measured based on nocturnal (9 hour) creatinine clearance; this was compared with various methods for estimation of GFR.ResultsThe mean 24-hour urine production increased significantly in both sexes across the expedition. But PVL reached significance only in males. No changes in Na+ in plasma, urine or its fractional excretion were seen at both altitudes. Urinary osmolality decreased upon ascent to the higher altitudes. ADH and PRA decreased significantly at both altitudes in males but only at HA2 in females. However, no changes in aldosterone were seen across the sexes and at different altitudes. ANP increased significantly only in males during the expedition. GFR, derived from 9-h creatinine clearance (CreaCl), decreased in both sexes at HA1 but remained stable at HA2. Conventional Crea[p]-based GFR estimates (eGFR) showed only poor correlation to CreaCl.ConclusionsWe report details of changes in hormonal patterns across high altitude sojourn. To our knowledge we are not aware of any study that has examined these hormones in same subjects and across gender during high altitude sojourn. Our results also suggest that depending on the estimation formula used, eGFR underestimated the observed decrease in renal function measured by CreaCl, thus opening the debate regarding the use of estimated glomerular filtration rates at high altitudes.

Hypobaric hypoxia induced renal damage is mediated by altering redox pathway

“…The increase in ventilatory response and diuresis during acute high altitude exposure appears to be an obligatory early phase of acclimatization to altitude. Moreover, volume regulation is considered one of the key physiological process central for both high altitude acclimatization, adaptation and mal-adaptation [ 5 ]. The strong positive correlation between the progression of kidney injury and decline in oxygen tension (pO 2 ) suggests the existence of causal involvement between hypoxemia and renal dysfunction [ 6 , 7 ].…”

“…Further, the risk of high altitude-induced kidney dysfunction and its systemic effects are also currently unclear. Except few case reports, there is not enough evidence (human or animal studies) that proves an association between altered kidneys function and increased incidence of high altitude induced systemic complications [ 5 , 9 ].…”

Chronic Hypobaric Hypoxia Modulates Primary Cilia Differently in Adult and Fetal Ovine Kidneys

“…The kidneys have a fundamental role in adaption to regulate body fluids, electrolyte and acid-base homeostasis during acclimatization to high altitude and in mountain sickness syndromes. Kidneys also respond to hypoxic diuresis and natriuresis through inhibition of renal tubular sodium reabsorption, in addition to erythropoietin production (Haditsch et al, 2015 ).…”

Renal Physiological Adaptation to High Altitude: A Systematic Review

“…Fourteen articles were included in the review (shown in Table 1 ). Renal tissue adaptation to altitude-induced hypoxia was either investigated in a rat model (Thron et al, 1998 ; Al-Hashem et al, 2012 or human model Lewis et al, 1997 ; Bestle et al, 2002 ; Cumbo et al, 2002 , 2015 ; Ge et al, 2002 ; Jefferson et al, 2002 ; Singh et al, 2003 ; Loeppky et al, 2005 ; Haditsch et al, 2007 , 2015 ; Pichler et al, 2008 ; Zouboules et al, 2018 ). Duration of exposure to high altitude ranged from 8 h (Loeppky et al, 2005 ) to 90 d (Al-Hashem et al, 2012 ), with an altitude up to 5,800 m above sea level (Singh et al, 2003 ).…”