A 21-year old brother of a person with insulin-dependent diabetes mellitus experienced increased urination and thirst for 6 weeks, along with a 15 pound weight losss, despitre a normal appetite. Fearing that these symptoms meant he also had developed diabetes mellitus, he did not seek medical attention promptly. However, when he developed nausea and vomiting for 48 hours, followed by a stuporous state, his college roommate insisted on taking him to the emergency room. There, he was found to ne semi-coherent and his mucous membranes and skin were dry. Blood pressure was 84/52 and pulse rate was 120 bpm. He was breathig deeply at a rate of 30 respirations per minute. The remainder of the examination was within normal limits. A urine sample contained a glucose concentration of 5% and tested strongly positive for acetoacetic acid. Plasma glucose was 800 mg/dl. Sodium was 132 mEq/L, bicarbonate was 5 mEq/l. chloride was 104 mEq/L and potassium was 5.8 mEq/L. Blood pH was 7.1, Pco2 was 17 mmHg and PO2 was 95 mmHg. Blood urea nitrogen was 28 mg/dl and plasma creatinine was 1.4 mg/dl. On treatment with insulin, intravenous fluids and potassium, the patient's clinical and biochemical status was restored to normal in 24 hours.
1.What is the cause if this pateint's very high plasma glucose level?
2.What are the mechanisms that elevated plasma glucose?
3.What has replaced bicarbonate in the patient's plasma, and by what mechanism?
4.Why is the blood pressure low and the pulse rate high?
5.What contributed to the pateint's weight loss?