BACKGROUND: Measurement of plasma-free metanephrine plus normetanephrine (PFM) is the best screening test for phaeochromocytoma. While clearly raised levels are diagnostic, borderline increases may be associated with factors such as stress and medications, and should prompt a repeat study after interfering factors are withdrawn.
METHODS: PFM results reported by a teaching hospital laboratory over a 12-month period were extracted from the laboratory information system. All borderline raised results were examined for a subsequent repeat test (as recommended by attached interpretative comment) and those not repeated were followed up by examination of case-notes or questionnaires to doctors.
RESULTS: Of 111 patients with borderline increased PFM which did not normalize on repeat measurement, 33 were from the hospital and 78 from outside locations. Hospital notes for 27 out of 33 hospital-patients (82%) could be reviewed, and 49 completed questionnaires (63% of 78 sent out) were received from outside locations. Of these 76 patients thus followed up, the test was not repeated in 55 (72%) cases with borderline increased PFM. Of 10 patients with an adrenal mass and borderline PFM, only three had PFM repeated. Of another nine patients with undetermined final diagnosis and borderline PFM, only three had the test repeated.
CONCLUSION: Seventy-two per cent of borderline increased PFM results were not followed up with appropriate repeat testing, potentially leading to missed detection of phaeochromocytoma. A stronger interpretative comment may encourage appropriate repeat testing in more cases with borderline increased PFM and suspected phaeochromocytoma.
IgA deficiency is the most common primary immunoglobulin deficiency. The prevalence in Caucasians is around one in 500, whereas in some Asian populations it is very uncommon. Most individuals with IgA deficiency are clinically asymptomatic. Those with symptoms of immunodeficiency have predominantly sinopulmonary or gastrointestinal infections, which are more severe when associated with IgG2, IgG4 or specific antibody deficiency. IgA deficiency is believed to be one end of a spectrum of immunodeficiency with common variable immunodeficiency at the most severe end. Although primary IgA deficiency is the most commonly encountered form, secondary deficiencies due to drugs or viral infections are recognized. IgA deficiencies can be partial or transient. Primary IgA deficiency is caused by a defect of terminal lymphocyte differentiation, which leads to underproduction of serum and mucosal IgA; affected individuals have normal IgA genes. A number of non-immunoglobulin genes have been implicated in IgA deficiency. There have been many diseases reported in association with IgA deficiency, particularly autoimmune diseases. The most common association is with coeliac disease (CD), which has special significance since CD is usually diagnosed by detection of specific IgA antibodies that are obviously lacking in IgA deficiency. There is no specific treatment for patients with symptomatic IgA deficiency. Antibiotics are prescribed in those with acute infections. A significant proportion of IgA-deficient individuals are reported to have anti-IgA antibodies in their serum. Although blood or blood products given to IgA-deficient individuals can lead to severe, even fatal, transfusion reactions, such reactions are rare.
A 35-year-old Malaysian man presented with rapid onset of flaccid quadriparesis associated with nausea and vomiting. General blood tests revealed severe hypokalaemia (serum potassium 1.5 mmol/L) and hypophosphataemia (serum phosphate 0.29 mmol/L) as a potential cause of the flaccid paralysis. Arterial blood gases showed mixed acid base disturbance of respiratory alkalosis and metabolic acidosis with hyperlactataemia. Thyrotoxic periodic paralysis (TPP) was suspected as the underlying cause of this presentation and thyroid function tests showed severe hyperthyroid results (free T4 > 77.2 pmol/L, free T3 19.3 pmol/L, thyroid-stimulating hormone [TSH] < 0.05 mIU/L). Treatment with intravenous potassium and phosphate infusion and oral propranolol resulted in rapid resolution of his symptoms. A discussion of the clinical and pathophysiological features and treatment of TPP (a very rare encounter in UK clinical practice) is presented, and to our knowledge associated hyperlactataemia has not been previously described.
Urinary hormone concentrations are often adjusted to correct for hydration status. We aimed to determine whether first morning void urine hormones in growing adolescents require adjustments and, if so, whether urinary creatinine or specific gravity are better adjustments.
The effect of ambient temperature on the analytical and clinical performance of a glucose meter was examined. A total of 114 venous whole blood samples were analysed for glucose by a reference method, and by a glucose meter at 21-22 degrees C, room temperatures, 26-27 degrees C and 33-34 degrees C. Glucose meter readings at each temperature were compared with the reference values and evaluated by analysis of variance, Spearman's correlation, the percentage of glucose meter readings within +/- 10% of the reference value and error grid analysis. Analysis of covariance was used to determine the effect of temperature on glucose meter readings. There were no significant differences in the glucose meter readings and in accuracy of the meter readings between different temperatures. Temperature was not a significant independent determinant of the glucose meter readings. For each glucose concentration, the precision of the meter and clinical performance were comparable between the different temperatures. In conclusion, ambient temperature does not affect the accuracy, precision and clinical performance of the Omnitest Sensor.
The lymphocyte subsets in the peripheral blood of healthy Malaysian adults (212 subjects, age 18-71 years) were analysed using a flow cytometer FACScan in an effort to establish a reference range for the lymphocyte subsets. The lymphocyte subsets studied were T cells (CD3), B cells (CD19), natural killer (NK) cells (CD3- CD16+/CD56+), helper/inducer cells (CD4), cytotoxic/suppressor cells (CD8) and the helper/suppressor ratio (CD4/CD8). The distributions of T cells, CD4 cells and CD8 cells were symmetric about their means while B cells, NK cells and CD4/CD8 ratio followed a skewed distribution. Differences in race were observed for T cells, NK cells, CD4 cells and CD4/CD8 ratio where the Indians were significantly different from the Malays and the Chinese (higher T cells, CD4 cells and CD4/CD8 ratio and lower NK cells). The B cells were significantly lower in the Chinese than the Malays and the Indians. Age differences were seen only in the Chinese where increased CD4 cells and CD4/CD8 ratio, and decreased CD8 cells were observed. A sex difference was observed only in the Chinese where the CD4/CD8 ratio was significantly higher in females than males.
A filter method for collection and storage of capillary blood spots for glycated haemoglobin (gHb) has been developed. Glass fibre filters (GFB) impregnated with 0.8 M boric acid were used to collect and store capillary blood. Haemoglobin from the dried blood spots was eluted into water and determined by Drabkin's method, while gHb in the eluates was determined by the microcolorimetric method. The intraassay coefficients of variation (CVs) were 4.5, 4.5 and 3.1% at 882, 1101 and 1704 pmol HMF/mg Hb, respectively. The corresponding inter-assay CVs were 8.6, 8.6 and 6.3%, respectively. A total of 63 paired capillary and venous blood samples were measured by both the direct and GFB method. The GFB method showed excellent correlation with the direct method (r = 0.948 and r = 0.994) after 7 and 14 days' storage at room temperature. The GFB method will enable prior collection and postage of blood samples by patients.
Background Plasma-free metanephrines (PFM) or urinary fractionated metanephrines (UFM) are the preferred biochemical tests for the diagnosis of phaeochromocytoma and paraganglioma (PPGL). Borderline increased results should be followed up to either exclude or confirm diagnosis. Methods We extracted all PFM and UFM results reported by our laboratory over a six-month period from the laboratory information system. We categorized patients with borderline increased results according to whether follow-up testing had been performed as suggested in the initial laboratory report. Questionnaires were then sent to all requesting doctors and medical notes reviewed where available. Results Two hundred and four patients with borderline increased PFM or UFM were identified. Sixty-five (38.5%) of 169 patients with borderline increased PFM had a repeat test out of which 36 were normal and 29 did not normalize. Of 35 patients with borderline increased UFM, 17 (48.6%) had subsequent PFM measurement, out of which 15 were normal. Questionnaires were returned to 106 (52%) patients. Of these, the most frequent indication for testing was hypertension ( n = 50); 15 patients had an incidental adrenal mass and two of these patients were diagnosed with a phaeochromocytoma. Conclusion Only 38% of patients with borderline increased PFM had a repeat PFM measurement. This was not significantly higher when compared with the 28% in a previous audit that we reported in 2010 ( P = 0.10). Forty-nine per cent of patients with a borderline increased UFM had a repeat UFM or PFM measurement. There remains a substantial possibility of missed detection of PPGL.