What does it mean if urine is dark yellow?

If urine is dark yellow, it typically indicates dehydration or concentrated urine. This color change occurs because when the body is dehydrated, the kidneys conserve water and produce less urine, resulting in a more concentrated solution. As the solute concentration increases, the urine takes on a deeper yellow hue due to the presence of waste products and pigments, like urochrome.

When properly hydrated, urine usually appears lighter in color, typically pale yellow or straw-colored. Therefore, a dark yellow color generally signals the need for increased fluid intake to achieve a better balance in hydration. While factors like urinary infections or prolonged fasting can also affect urine color, the most direct interpretation of dark yellow urine is its association with dehydration.