Secretory tumors of the pituitary gland: a clinical biochemistry perspective.

The pituitary gland is responsible for the production and/or secretion of various hormones that play a vital role in regulating endocrine function within the body. Secretory tumors of the anterior pituitary predominantly, pituitary adenomas, collectively account for 10%-25% of central nervous system tumors requiring surgical treatment. The most common secretory tumors are prolactinomas, which can be diagnosed by basal prolactin levels. Acromegaly can be diagnosed by basal insulin growth-like factor 1 levels and the failure of growth hormone (GH) to suppress during an oral glucose tolerance test. Cushing disease can be diagnosed by demonstrating hypercortisolemia evidenced by increased salivary cortisol levels in the evening, increased urine free cortisol excretion and failure of plasma cortisol to suppress following oral dexamethasone given overnight (1.0 mg). We also discuss the diagnosis of the rarer thyroid-stimulating hormone and gonadotrophin secretory tumors. Morbidity is associated with tumor occurrence, clinical sequelae as well as the related medical, surgical and radiological management. This review focuses on the pathogenesis of secretory tumors of the anterior pituitary with emphasis on molecular mechanisms associated with tumorigenesis and the major role of the clinical chemistry laboratory in diagnosis and management of these tumors.

Evaluation of the revised Schwartz creatinine-based glomerular filtration rate estimating equation in Black African children in KwaZulu-Natal, South Africa.

Background The use of serum creatinine equations for estimating glomerular filtration rate is well known in adults and children. We evaluated the revised Schwartz creatinine-based estimated glomerular filtration rate prediction equation in Black African children in KwaZulu-Natal, South Africa. Methods Review of medical records of all Black African patients aged 2-18 years old who have had glomerular filtration rate determined by intravenous Technetium-99 m-diethylene-triamine-pentaacetate, for the period 1 January 2010 to 31 December 2014 at the Inkosi Albert Luthuli Central Hospital, Durban, South Africa was performed. Estimated glomerular filtration rate result obtained using the revised Schwartz equation was compared to Technetium-99 m-diethylene-triamine-pentaacetate plasma clearance measured glomerular filtration rate. Accuracy of the estimated glomerular filtration rate equations within 10% (P10) and 30% (P30) of the measured glomerular filtration rate, sensitivity and specificity for predicting glomerular filtration rate < 60 mL/min/1.73 m2 and < 30 mL/min/1.73 m2 was determined. Results Results from 148 African children between 2 and 18 years old were analysed. P10 and P30 values were 16 and 49%, respectively. Sensitivity of 92.9% (95% CI: 80.5-85), specificity of 95.3 (95% CI: 89.3-98.5) and AUC of 0.96 (95% CI 0.92-0.99) were obtained for measured estimated glomerular filtration rate < 60 mL/min/1.73 m2. Sensitivity of 88.2% (95% CI: 63.6-98.5), specificity of 90.8 (95% CI: 84.5-95.2) and area under the curve of 0.93 (95% CI 0.88-0.96) were obtained for measured estimated glomerular filtration rate < 30 mL/min/1.73 m2. Conclusions The revised Schwartz equation did not meet the National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines of 90% of estimated glomerular filtration rate results within 30% of measured glomerular filtration rate.

An audit of immunofixation requesting practices at a South African referral laboratory.

BACKGROUND: It is common practice in most chemical pathology laboratories for reflective immunofixation electrophoresis (IFE) to occur following the detection or suspicion of a paraprotein on serum protein electrophoresis (SPEP). The chemical pathology laboratory at Inkosi Albert Luthuli Central Hospital (IALCH) in Durban, South Africa, is currently the only non-private laboratory in the KwaZulu Natal province that performs SPEP analysis, with current practice requiring that the clinician request IFE following suggestion by the laboratory after a suspicious SPEP result. OBJECTIVES: To review the current process for IFE at IALCH in the context of reflective testing and to examine the use of the alpha-2-globulin/alpha-1-globulin ratio as a predictor of a positive IFE result. METHODS: Data for 1260 consecutive SPEP tests performed at the IALCH National Health Laboratory Service were collected between February and July 2011. SPEP and IFE were performed with a Sebia Hydrasys automated electrophoresis system. The alpha-2-globulin/alpha-1-globulin ratio was calculated using density of corresponding fractions on SPEP. RESULTS: Analysis revealed that of the 1260 SPEPs performed during the analysis period, 304 IFEs were suggested by the reviewing pathologist. A total of 45 (15%) of the suggested IFEs were subsequently requested by the attending clinicians. Almost half (46.5%) (n = 20) of the suggested IFEs that were performed revealed the presence of a paraprotein. There was no statistically-significant difference between the alpha-2-globulin/alpha-1-globulin ratio for patients with positive or negative IFEs (p-value = 0.2). CONCLUSIONS: This study reveals the need for reflective addition of IFE testing by the laboratory following suspicious findings on SPEP.