A low specific gravity is a manifestation of which condition?

A low specific gravity is a manifestation of which condition?

• A. Diabetes insipidus
• B. SIADH
• C. Acute kidney injury
• D. Hypothyroidism

Answer: (B)

Urine specific gravity reflects how concentrated the urine is. A low value means the urine is very dilute, which happens when the kidneys can’t concentrate water properly. The classic scenario for this is diabetes insipidus, where a deficiency of antidiuretic hormone (or resistance to its effect) prevents water reabsorption in the collecting ducts. As a result, large volumes of dilute urine are produced, giving a low specific gravity. In contrast, SIADH involves excess ADH causing the urine to be concentrated, so its specific gravity is high rather than low. Acute kidney injury and hypothyroidism are not typical causes of dilute urine; their effects on urine concentration aren’t as direct or consistent with a low specific gravity.

Urine specific gravity reflects how concentrated the urine is. A low value means the urine is very dilute, which happens when the kidneys can’t concentrate water properly. The classic scenario for this is diabetes insipidus, where a deficiency of antidiuretic hormone (or resistance to its effect) prevents water reabsorption in the collecting ducts. As a result, large volumes of dilute urine are produced, giving a low specific gravity.

In contrast, SIADH involves excess ADH causing the urine to be concentrated, so its specific gravity is high rather than low. Acute kidney injury and hypothyroidism are not typical causes of dilute urine; their effects on urine concentration aren’t as direct or consistent with a low specific gravity.