Chapter 6 Answers to self check questions

1 Ketones build up in the body when the body metabolizes fats instead of carbohydrates to provide energy. This occurs when the body has insufficient insulin to allow the transport of glucose from the bloodstream into the cells. In this circumstance ketones build up in the blood and are excreted in the urine and this is a common complication of poorly controlled diabetes. This situation, if left untreated, can lead to ketoacidosis, a condition which may be life-threatening. It is appropriate, therefore, to test the urine for ketones at regular intervals.

2 ‘Ketostix’ are thin strips of plastic, impregnated with a nitroprusside reagent, which are dipped into the patient’s urine. Acetoacetic acid (the ketones – check the structure) reacts with sodium nitroferricyanide (nitroprusside) and glycine to produce a purple complex. The depth of the colour of the complex indicates the level of ketones in the urine.