Presented by Richard Hillman, M.D. - Columbia, Missouri
DNPH is a test that measures keto acids, ketones and acetones. Normal newborns do not excrete ketones; their brains are using the ketones produced by the body. DNPH will test positive when the BCAAs are elevated in a child with MSUD. It is a good test to use for home monitoring.
Use an equal amount of urine and reagent. When the reading is negative, it looks very much like the reagent. If the reading is cloudy, the individual with MSUD has elevated levels. If the reading shows a precipitate (settlement on the bottom of the test tube), illness is definitely indicated. The solution gets more orange with time after it is mixed. It is best to read the test right after the urine is added.
DNPH is a strong acid that will eat through material. Refrigerating the solution in a dark bottle will extend the shelf life, but the solution should warm up before it is used to catch a slightly positive reading. It is possible to get a false positive with old DNPH. Do a test on a person who does not have MSUD to check it.
Newborns often produce a slightly cloudy reading that is false. A slightly cloudy solution can be falsely positive due to the gels in the new disposable diapers. Also the urine of babies is often mixed with stool. In addition, two antibiotic prescriptions for newborns cause false positive readings.
Vaginal discharge can also cause false positive readings in older girls. A clean catch urine sample must be taken to avoid these false readings. DNPH is very important for testing older children who are harder to judge if their levels are off. One sign of high levels is deterioration in handwriting.
Ketosticks measure ketones that are not from MSUD, but produced from fat breakdown, such as when a person is very ill or has fasted. DNPH is much more sensitive.
Dr. Hillman demonstrated the DNPH by using the urine from a baby with MSUD, who was sick at the time. The reaction was very positive with an immediate, very cloudy (opaque) reaction.
A closer look at home monitoring techniques
- Written by Joyce Brubacher