Certified Hospice and Palliative Assistant (CHPNA) Practice Test 2025 - Free CHPNA Exam Practice Questions and Preparation Guide

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is characterized by the excessive release of antidiuretic hormone (ADH) despite normal or low plasma osmolality. This condition leads to the kidneys reabsorbing more water, which in turn dilutes the plasma, resulting in lower plasma osmolality.

In SIADH, urine becomes concentrated because ADH encourages water retention. Consequently, the urine osmolality is higher than the plasma osmolality. This is a key diagnostic criterion for SIADH, as it signifies that the kidneys are excreting a concentrated urine while the body is retaining fluid, showcasing the inappropriate nature of ADH secretion in this syndrome.

The other options do not align with the pathophysiology of SIADH. Higher plasma osmolality than urine osmolality suggests normal renal function and is indicative of conditions such as dehydration or hypernatremia. Normal levels of urinary sodium and osmolality would not indicate SIADH since the condition is associated with increased sodium excretion. Lastly, lower urine osmolality than plasma osmolality would suggest a different issue, such as diabetes insipidus, where the kidneys cannot concentrate urine properly. Thus,