Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2013) 31 P251 | DOI: 10.1530/endoabs.31.P251

SFEBES2013 Poster Presentations Pituitary (71 abstracts)

Altitude acclimatization: plasma AVP response and physiological changes

Meenakshi Sachidhanandam , Ashok Kumar Salthan , Som Nath Singh & UdaySankar Ray

Defence Institute of Physiology and Allied Sciences, Delhi, India.

Background: Arginine vasopressin (AVP) changes during altitude acclimatization is of clinical interest as increases in their plasma levels (with reference to sea-level (SL)) have been associated with fluid retention accompanied by elevated plasma cortisol levels. Studies have reported no change/ decrease in plasma AVP during ‘normal’ acclimatization. This study was conducted to evaluate plasma AVP changes and the associated physiological changes during chronic exposure to high-altitude (HA).

Methods: Healthy, male volunteers (n=36) between 20–50 years of age were recruited for the study. Subjects were evaluated both at SL and HA (4500 m, 3–4 weeks of stay) for the following parameters: plasma cortisol (CORT) and AVP (ELISA), haemoglobin(Hb), hematocrit(Hct), plasma sodium (Na); total protein (PROT), body weight (BW), arterial oxygen saturation (SaO2), heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP). Values are mean±S.D.

Results: At HA, all subjects were asymptomatic and exhibited physiological characteristics of altitude acclimatization (↓: BW, SaO2; ↑: Hb, Hct, MAP, HR; ↔: RR). Plasma AVP and CORT level during HA exposure was within ‘SL normal range’. Subjects were categorized as follows:

Table 1
Category AVPSLvsHAnSLHAP valueSLHAP valuePROT/Na
I (↔)80.7±0.20.7±0.2>.0510.0±3.08.6±3.6>.05
II (↓)160.9±0.20.6±0.2<.0510.7±3.111.7±4.6>.05
III (↑)120.6±0.10.9±0.2<.059.9±1.912.3±2.8<.05↑/↔

Conclusions: Altitude acclimatization is characterised by physiological variation in both plasma AVP and CORT levels. However, the significance of ‘subtle’ changes in AVP with regard to body fluid regulation (re-setting of osmotic threshold) needs further evaluation.

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