Which analytes are typically elevated when changing position from supine to upright?

The correct choice is related to the hemodynamic changes that occur when a person moves from a supine (lying down) position to an upright (standing) position. When a person stands up, several physiological responses are triggered, influencing the levels of certain hormones and substances in the blood.

Albumin, a major protein in the blood, can show concentration changes because of shifts in plasma volume. Upon standing, there is a mobilization of fluid from the intravascular space (blood vessels) to the extravascular space (the interstitial tissues). This fluid movement can cause a relative increase in blood albumin concentration as the overall plasma volume decreases.

Calcium levels can also be influenced by changes in position, primarily due to changes in the distribution of body fluids and the balance of calcium in circulation. However, the primary analytes that demonstrate significant changes upon position change are traditionally related to the regulation of fluid and electrolytes, hence the relevance of albumin.

In contrast, the other choices do not reflect typical changes in analyte levels associated with postural shifts. For example, while ACTH and cortisol are responsive to stress and circadian rhythms, they are not primarily influenced by a postural change. Aldosterone and insulin levels can indeed fluctuate