Part of that extra thickness is caused by the protein keratin, which is nourished in deeper layers of the skin but forms a surface layer of dead cells on the epidermis. This extra thickness may also explain why your hands and feet become wrinkled when you soak in the tub.
Antidiuretic hormone (ADH), also called arginine vasopressin (AVP), is a hormone that helps regulate water balance in the body by controlling the amount of water the kidneys reabsorb while they are filtering wastes out of the blood. This test measures the amount of ADH in the blood.
With ADH suppression or stimulation tests, a health practitioner is looking for appropriate levels of ADH, osmolality, and kidney water retention responses. 1  A water loading ADH suppression test may be used to help diagnose SIADH.2  With this test, those with SIADH typically have decreased blood sodium and osmolality. With this test, those with SIADH typically have decreased blood sodium and osmolality. 2  They do not produce as much urine as expected, urine osmolality is high relative to serum osmolality, and the ADH concentration is in excess of what would be appropriate and does not decrease appropriately with water loading.