Bland-Altman plot of clinically unacceptable agreement of measured and calculated plasma osmolality
for juvenile rehabilitated black-bellied whistling ducks.
(2011b) clarified whether or not increases in plasma osmolality
and subsequent thirst sensation produced by dry forage feeding suppress dry forage intake.
, sodium and potassium concentrations.
The patient's plasma sodium level was low (120 mmol/L), as well as her plasma osmolality
(235 mOsm/kg), while urinary sodium and osmolality levels were both high.
Increased plasma osmolality
further stimulates ADH secretion and promotes water retention.
Plasma glucose was measured spectrophotometrically (Sigma, kit 16-20), and plasma osmolality
was determined with a vapor pressure osmometer (Wescor, model 5500, Logan, UT).
Decreased plasma osmolality
causes cellular swelling.
Normal values which rule out ADH deficiency are as follows: (a) urine osmolality 500-1400 mOsm/L, (b) plasma osmolality
288-291 mOsm/L, (c) plasma osmolality
: urine osmolality [is greater than] 2, and (d) urine specific gravity [is greater than] 1.010 (Johnson, 1993).
Thus, in one study of elderly people there was a greater release of AVP in response to increasing plasma osmolality
, although the age range of the subjects was only 52-66 years.
Increase in plasma osmolality
or decrease in blood volume leads to secretion of arginine vasopressin (AVP), also called antidiuretic hormone (ADH), from the posterior pituitary gland (4,5).
The water deprivation test showed elevated serum Na+, plasma osmolality
, and urine osmolality (Table 2).
This was repeated twice with similar results and a measured plasma osmolality
was 403 mOsm/kg.