Annals of clinical biochemistry
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Ann. Clin. Biochem. · May 2008
Revised national guidelines for analysis of cerebrospinal fluid for bilirubin in suspected subarachnoid haemorrhage.
It is crucially important to detect subarachnoid haemorrhage (SAH) in all patients in whom it has occurred to select patients for angiography and preventative surgery. A computerized tomography (CT) scan is positive in up to 98% of patients with SAH presenting within 12 h, but is positive in only 50% of those presenting within one week. Cerebrospinal fluid (CSF) bilirubin spectrophotometry can be used to determine the need for angiography in those few CT-negative patients in whom clinical suspicion of SAH remains high; it may remain positive up to two weeks after the event. ⋯ Store the supernatant at 4 degrees C in the dark until analysis. An increase in CSF bilirubin is the key finding, which supports the occurrence of SAH but is not specific for this. In most positive cases, bilirubin will occur with oxyhaemoglobin.
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Ann. Clin. Biochem. · Mar 2008
What is the role of cerebrospinal fluid ferritin in the diagnosis of subarachnoid haemorrhage in computed tomography-negative patients?
Spectrophotometry of cerebrospinal fluid (CSF) for bilirubin is the recommended method for investigation in suspected cases of subarachnoid haemorrhage (SAH), when a computed tomography (CT) of the head is negative for blood. There is a potential need for a simpler alternative. Measurement of CSF ferritin might fulfil this need. ⋯ At an appropriate negative predictive value (1.0) for a rule-out test, ferritin has too low a specificity to function as a stand-alone test and we cannot recommend it as an initial screen to be followed by spectrophotometry.
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Ann. Clin. Biochem. · Nov 2007
Comparative StudyComparison of three commercial tests for buprenorphine screening in urine.
Rapid and sensitive tests for detecting buprenorphine and its metabolites for drug-screening situations have been long awaited. From the tests available, we have evaluated two on-site drugs-of-abuse testing devices using competitive binding immunoassays and one homogeneous enzyme immunoassay measured on an automated analyser. ⋯ Our results indicate that special care should be taken when selecting immunology-based point-of-care methods for measurement of buprenorphine.
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Ann. Clin. Biochem. · Sep 2007
ReviewVasopressin and disorders of water balance: the physiology and pathophysiology of vasopressin.
Disorders of water balance are a common feature of clinical practice. An understanding of the physiology and pathophysiology of the key endocrine regulator of water balance vasopressin (VP) is key to diagnosis and management of these disorders. Diabetes insipidus is the result of a lack of VP or (less commonly) resistance to the renal effects of the hormone. ⋯ A comprehensive assessment of cardiovascular status and pharmacological influences are needed in these circumstances to differentiate between primary (inappropriate) and secondary (appropriate) physiological VP production. As with diabetes insipidus, diagnostic testing can help define the aetiology of hyponatraemia and direct appropriate management. Patients with disorders of water balance benefit from a joint clinical and laboratory medicine approach to diagnosis and management.
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Ann. Clin. Biochem. · Jul 2007
Case ReportsHigh anion gap metabolic acidosis secondary to pyroglutamic aciduria (5-oxoprolinuria): association with prescription drugs and malnutrition.
Two cases of High Anion Gap Metabolic Acidosis (HAGMA) due to pyroglutamic acid (5-oxoproline) are described. In both cases the HAGMA developed during an episode of hospital treatment, in conjunction with paracetamol and antibiotic prescription, and the surviving patient made an uneventful recovery after the drugs were withdrawn. Clinicians need to be aware of this cause for metabolic acidosis because it may be a more common metabolic disturbance in compromised patients than would be expected, and the discontinuation of drugs implicated in the aetiology is therapeutic.