Final answer:
A urine specific gravity of 1.020 indicates that DDAVP is effective in treating diabetes insipidus by increasing urine concentration through enhanced water reabsorption, which is the intended effect of this medication.
Step-by-step explanation:
The subject of this question is Medicine, and it appears to be at a College level, focusing on the treatment and lab indications of diabetes insipidus with desmopressin acetate (DDAVP). The lab finding that indicates that DDAVP is having its intended effect for a client with diabetes insipidus is urine specific gravity 1.020. Diabetes insipidus is characterized by the production of copious amounts of very dilute urine (polyuria) and an increased thirst (polydipsia). DDAVP is a synthetic analog of antidiuretic hormone (ADH), which acts to decrease urine production by increasing water reabsorption in the kidney's collecting ducts. An effective response to DDAVP would manifest as an increased urine specific gravity, indicating more concentrated urine and, consequently, improved water reabsorption.