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Table 1 Summary of included trials investigating the threshold of AVP release and thirst stimulation in response to increasing plasma osmolality

From: The sensitivity of the human thirst response to changes in plasma osmolality: a systematic review

Author (year) (citation) Age mean Subject condition Sample size Dehydration mechanism Thirst threshold mean (±SD) mOsm/kg Relevant findings
(Thompson, Bland et al. 1986) 24.3 Healthy 10 5% NaCl @ 0.06 ml/kg/min for 2 h 281.1 ± 3.2 High individual repeatability of threshold results. Lower threshold found, stimulating thirst before significant dehydration occurs.
(Phillips, Bretherton et al. 1991) 25 69.8 Healthy Young Healthy Elderly 7 7 5% NaCl @ 0.06 ml/kg/min for 2 h 261.0 ± 18.5 276.0 ± 13.2 Elderly show reduced thirst
(Davies, O'Neill et al. 1995) 26.8 70.5 Healthy Young Healthy Elderly 10 10 5% NaCl @ 0.1 ml/kg/min for 2 h 287.5 ± 12.6 292.4 ± 8.5 Thirst threshold is not elevated in healthy elderly, but inter-subject variation is greater. Linear response of thirst to pOsm identified.
(Thompson and Baylis 1987) 29.2 28.6 Healthy Controls Diabetes insipidus 15 14 5% NaCl @ 0.06 ml/kg/min for 2 h 286.3 ± 3.9 286.3 ± 3.9 Diabetes insipidus does not alter thirst or AVP response to pOsm
(Thompson, Davis et al. 1988) 30 29.1 Healthy Controls Type 1 Diabetes 7 7 5% NaCl @ 0.1 ml/kg/min for 2 h vs: Glucose raised from 4 to 20 mmol/l over 2 h 284.7 ± 1.6 287.0 ± 6.9 Oral fluid intake rapidly abolished thirst independent of pOsm. Type 1 Diabetes does not alter thirst and AVP response.
(Thompson, Edwards et al. 1991) 29.6 Healthy controls 7 5% NaCl @ 0.05 ml/kg/min for 2 h 286.5 ± 3.2 No significant difference between thirst and AVP thresholds.
(Thompson, Selby et al. 1991) 34.1 Healthy 16 5% NaCl @ 0.06 ml/kg/min for 2 h 286.3 ± 4.2 Very high 6 month repeatability of AVP and thirst threshold seen within individuals
(Argent, Burrell et al. 1991) 41.1 41.4 Healthy Chronic Kidney Disease 7 8 5% NaCl @ 0.06 ml/kg/min for 2 h 279.4 ± 5.8 281.8 ± 6.8 Threshold of AVP & Thirst are very close in both subject groups
(Phillips, Butler et al. 1994) 41.5 Healthy 8 5% NaCl @ 0.06 ml/kg/min for 2 h vs. 20% Mannitol @ 0.07 ml/kg/min for 2 h 291.0 ± 5.8 5% saline is a more powerful osmotic stimulant than mannitol. The threshold for mannitol is similar but the slope lower
(Martinez-Vea, Garcia et al. 1992) 43.1 55.0 Healthy Controls Chronic Kidney Disease 6 5 5% NaCl @ 0.06 ml/kg/min for 2 h 289.8 ± 8.3 288.9 ± 19.0 High degree of sensitivity and repeatability in individual responses of thirst to osmolality. Thirst unaffected by chronic kidney disease, but dialysis causes a variation.
(Smith, Moore et al. 2004) 51.8 Healthy Controls 8 5% NaCl @ 0.05 ml/kg/min for 2 h 285.9 ± 2.8 Oral fluid intake abolishes osmotically stimulated thirst. Some individuals can lack thirst response.
(McKenna, Morris et al. 1999) 69.8 70.5 Healthy Controls Type 2 Diabetes 7 7 8 h water deprivation 285.5 ± 2.5 283.9 ± 2.0 Osmoregulation of thirst and AVP are normal in Type 2 Diabetes.