Q & A for ketone body metabolism
Q１ Blood ketone body was 3,000 mmol/L in infantile vomiting and diarrhea. Should I consider inborn errors of metabolism for the diagnosis?
Q２ A two-years old child with convulsion had hypoglycemia (30mg/dl) in emergency room. Blood ketone level was 5,000 mmol/L at that time.
Is this ketone body level abnormal?
Q３ A two-years old child with convulsion had hypoglycemia (30mg/dl) in emergency room. Blood keotne level was 1,000 mmol/L at that time.
Is this ketone body level abnormal?
Q４ Urine from a neonate had ketone 2+. Is this ketone body level abnormal?
Q５ A neonate whose sucking was not so good had blood ketone level of 1, 000 mmol/L. Is this ketone body level abnormal?
Q６ I understand importance of blood gas data in ketoacidotic crisis, but what should we do in a clinic where blood gas analysis is not available.
Q７ What kind of analysis should I do with patients with recurrent ketosis, such as acetonemic vomiting and ketotic hypoglycemia, to rule out disorders in ketone body metabolism.
Q１ Blood ketone body was 3,000 mmol/L in infantile vomiting and diarrhea. Should I consider inborn errors of metabolism for the diagnosis?
A1 In patienst with infantile diarrhea ketone body production is induced, so it is common that such patients have ketone body level of 3,000~5,000 mmol/L. Free fatty acid level is also induced to 2 mmol/L or more.
Q２ A two-years old child with convulsion had hypoglycemia (30mg/dl) in emergency room. Blood ketone level was 5,000 mmol/L at that time.
Is this ketone body level abnormal?
A2 The patient already became hypoglycemia (30mg/dl). Ketone body is usually induced before hypoglycemic condition. So, it is reasonable that blood ketone level became 5,000 mmol/L as a physiological response.
Q３ A two-years old child with convulsion had hypoglycemia (30mg/dl) in emergency room. Blood ketone level was 1,000 mmol/L at that time.
Is this ketone body level abnormal?
A3 As mentioned in Q2, if the patient became hypoglycemia, ketone body level was expected to be high (more than 3,000 mmol/L). Hence the ketogenic response is insufficient comparing to glucose level. If free fatty acid level was more than 2mM, you should consider disorders in fatty acid beta-oxidation or ketone body synthesis.
Q４ Urine from a neonate had ketone 2+. Is this ketone body level abnormal?
A4 It is well-known that physician should consider inborn errors of metabolism as possible diagnosis, if a neonate has positive urinary ketone.
Your judgment for Q4 should be “abnormal”. You may measure blood glucose, blood gas analysis, ammonia, blood ketones, and free fatty acids and perform urinary organic acid analysis. Possible differential diagnosesare neonate-onset organic acidurias such as methylmalonic acidemia, propionic acidemia, and isovaleric acidemia, or succinyl-CoA:3-ketoacid CoA transferase deficiency.
Q５ A neonate whose sucking was not so good had blood ketone level of 1,000 mmol/L. Is this ketone body level abnormal?
As mentioned in A4, neonatal positive urinary ketone indicate a sign for metabolic disorders, but neonates have sometimes high blood ketone body levels. So, the level of 1,000 mmol/L is not concluded to abnormal immediately. However, you may measure glucose, blood gas, free fatty acids for evaluation. Neonates drinking maternal milk have a tendency of higher blood ketone body level, as well as free fatty acid level, than neonates drinking artificial milk.
Q６ I understand importance of blood gas data in ketoacidotic crisis, but what should we do in a clinic where blood gas analysis is not available.
A6 If ketoacidosis is severe, patients develop polypnea and dyspnea.
So, if you see a patient who has strongly positive urinary ketones and polypnea, you should consider that the patient has severe metabolic acidosis and should ambulance the patient to the hospital for diagnosis and treatment.
Q７ What kind of analysis should I do with patients with recurrent ketosis, such as acetonemic vomiting and ketotic hypoglycemia, to rule out disorders in ketone body metabolism.
A7 I recommended to check blood glucose, blood gas, ammonia, free fatty acids, ketone bodies in a typical attack, to confirm pH >7.3, HCO3 >15 mmol/L, free fatty acids/ totak ketone bodies ratio >0.3 Especially, evaluation in the first attack is recommended. Endocrine evaluation is also recommended for recurrent cases.