Patient Study

0469659 Patient study A case of low blood glucose causing unconsciousness Clinical features Patient is a 27 year old female registered nurse, she was admitted in a coma with a blood glucose level of 1 mmol/1 her symptoms point to neuroglycopenia caused from hypoglycaemia but cause for hypoglycaemia is unclear as Blood test were done for liver function which came back normal and a CAT scan was done that was normal. Investigations The patient has neuroglycopenia cause by hypoglycaemia. Neuroglycopenia is the shortage of glucose in the brain due to hypoglycaemia. It affects the functions of neurons and alters brain function and behaviour. Prolonged neuroglycopenia can result in permanent brain damage. Nussey and Whitehead 2001. Hypoglycemia is the pathologic state produced by a lower than normal amount of sugar (glucose) in the blood. Hypoglycemia can produce a variety of symptoms and effects but the principal problems arise from an inadequate supply of glucose as fuel to the brain, resulting in impairment of function neuroglycopenia. Hundreds of conditions can cause hypoglycemia so blood tests were taken to investigate her liver, thyroid and kidney function all the tests came back normal. A CAT scan was done but results came back normal so insulinoma is unlikely, glycogen storage disease is unlikely because most appear in childhood and alcohol induced hypoglycaemia is unlikely as no alcoholic symptoms. Addison's disease could be considered but symptoms don’t fit diagnoses can be done by testing adrenal hormone levels if they are low after stimulation with synthetic pituitary hormone. Diagnoses The patient has neuroglycopenia caused by severe hypoglycaemia. The cause of hypoglycaemia is unclear because the patients insulin levels were high 82u/ml (normal reference range 0-29) and c-peptides were undectable. The high insulin levels and low c-peptide levels could be from a small insulinoma that was missed by the CAT scan. Factitious hypoglycaemia should be considered, this is an attempt to induce a low serum glucose level by taking oral insulin Waickus CM et al 1999. Commercially available human insulin does not contain c- peptide so in the case of diagnosing Factitious hypoglycaemia circulating concentrations of insulin would be high but cpeptide would be low; Nussey and Whitehead 2001.Because factitious hypoglycaemia is rare an MRI should be done of the pancreas to determine if there is an insulinoma that was missed by the CAT scan. Discussion Blood glucose levels are tightly controlled and stay within narrow limits throughout the day , the normal reference range is 3.5-6.0mmol.1, levels rise

0469659 after meals and are usually lowest in the morning before the first meal of the day Marieb 2004. The brain is dependent on glucose as its sole fuel. The brain does not store glucose so it requires a continuous supply of glucose. Glucose is transported into brain cells by the glucose transporter GLUT 3, Glucose is the only energy source that can pass through your blood-brain barrier Insulin is the principal hormone responsible for the control of glucose metabolism. It is synthesized in the b cells of the islets of langerans as the precursor, proinsulin, which is processed to form c-peptide and insulin. Berg et al 2005. The c-peptide of proinsulin is important for the biosynthesis of insulin. It connects the A and B chains of insulin in the proinsulin molecule, Nussey and Whitehead 2001. Cleaved C-peptide is co-secreted with insulin but is not cleared by the liver and has a longer t1/2 in the systemic circulation. Treatment and prognosis On admittance the patient was given an iv of glucose until blood glucose was in normal range. Because the cause of hypoglycaemia is unclear further investigation needs to be done, if the MRI shows a small insulinoma the next step is surgical removal of the insulinoma. Most patients with benign insulinoma can be cured with surgery. Persistent or recurrent hypoglycemia after surgery tends to occur in patients with multiple tumors. If MRI results are clear then factitious hypoglycaemia should be seriously considered because all other physical tests are normal the patient would be referred to a psychiatrist. The prognosis in most cases is working towards managing the disorder in a long term way rather then try and curing it, as there is no known cure.