The results of laboratory tests have a substantial role in the diagnosis and management of disease. However, laboratory results do not always correspond with the patient's clinical status. Unexpected results may arise from factors other than disease. The total testing process consists of 3 separate phases — pre-analytical, analytical, and post-analytical. The accuracy and reliability of a laboratory result depend on the quality of each phase. In this article, the common variables in the pre-analytical and post-analytical phases and their effect on test result quality in primary care are reviewed.

For many years, the clinical laboratory's focus on analytical quality has resulted in an error rate of 4-5 sigma, which surpasses most other areas in healthcare. However, greater appreciation of the prevalence of errors in the pre- and post-analytical phases and their potential for patient harm has led to increasing requirements for laboratories to take greater responsibility for activities outside their immediate control. Accreditation bodies such as the Joint Commission International (JCI) and the College of American Pathologists (CAP) now require clear and effective procedures for patient/sample identification and communication of critical results. There are a variety of free on-line resources available to aid in managing the extra-analytical phase and the recent publication of quality indicators and proposed performance levels by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) working group on laboratory errors and patient safety provides particularly useful benchmarking data. Managing the extra-laboratory phase of the total testing cycle is the next challenge for laboratory medicine. By building on its existing quality management expertise, quantitative scientific background and familiarity with information technology, the clinical laboratory is well suited to play a greater role in reducing errors and improving patient safety outside the confines of the laboratory.
Clinical Laboratory Techniques/standards ; Diagnostic Errors ; Humans ; Laboratories/*standards ; Quality Assurance, Health Care/standards ; Specimen Handling

No abstract available.
Adult ; Aged ; Asian Continental Ancestry Group/ethnology ; China ; Cholecalciferol/*analysis ; Ergocalciferols/*analysis ; Female ; Humans ; Immunoassay ; India ; Malaysia ; Male ; Middle Aged ; Reagent Kits, Diagnostic ; Young Adult

Changes in renal function are one of the most common manifestations of severe illness. There is a clinical need to intervene early with proven treatments in patients with potentially deleterious changes in renal function. Unfortunately progress has been hindered by poor definitions of renal dysfunction and a lack of early biomarkers of renal injury. In recent years, the definitional problem has been addressed with the establishment of a new well-defined diagnostic entity, acute kidney injury (AKI), which encompasses the wide spectrum of kidney dysfunction, together with clearer definition and sub-classification of the cardio-renal syndromes. From the laboratory have emerged new biomarkers which allow early detection of AKI, including neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C. This review describes the new concepts of AKI and the cardio-renal syndromes as well as novel biomarkers which allow early detection of AKI. Panels of AKI biomarker tests are likely to revolutionise the diagnosis and management of critically ill patients in the coming years. Earlier diagnosis and intervention should significantly reduce the morbidity and mortality associated with acute kidney damage.
Acute Kidney Injury/*diagnosis ; Biological Markers/analysis/blood/urine ; Cystatin C/blood/urine ; Heart Failure/complications/etiology ; Humans ; Kidney Diseases/complications/*diagnosis/etiology ; Lipocalins/blood/urine ; Syndrome

INTRODUCTIONIn a patient with hyperthyroidism, the detection of elevated thyroid hormone concentration with measurable thyroid-stimulating hormone (TSH) value poses considerable diagnostic difficulties.

CLINICAL PICTUREThis 38-year-old lady presented with clinical features of thyrotoxicosis. Her serum free thyroxine concentrations were unequivocally elevated [45 to 82 pmol/L (reference interval, 10 to 20 pmol/L)] but the serum TSH values were persistently within the reference interval [0.49 to 2.48 mIU/L (reference interval, 0.45 to 4.5 mIU/L)].

TREATMENTInvestigations excluded a TSH-secreting pituitary adenoma and a thyroid hormone resistance state and confirmed false elevation in serum TSH concentration due to assay interference from heterophile antibodies. The patient was treated with carbimazole for 18 months.

OUTCOMEThe heterophile antibody-mediated assay interference disappeared 10 months following the initiation of treatment with carbimazole, but returned when the patient relapsed. It disappeared again 2 months after the initiation of treatment.

CONCLUSIONSClinicians should be aware of the potential for interference in immunoassays, and suspect it whenever the test results seem inappropriate to the patient's clinical state. Misinterpretation of test values, arising as a result of assay interference, may lead to misdiagnosis, unnecessary and at times expensive investigations, delay in initiation of treatment and worst of all, the initiation of inappropriate treatment.

Adenoma ; diagnosis ; Adult ; Antibodies, Heterophile ; analysis ; immunology ; Diagnostic Errors ; Female ; Graves Disease ; diagnosis ; Humans ; Immunoassay ; Pituitary Neoplasms ; diagnosis ; Thyrotoxicosis ; blood ; diagnosis ; immunology ; Thyrotropin ; blood ; Thyroxine ; blood

Serum testosterone immunoassay interference may cause falsely high results. We report a case of 20-year-old female with PCOS whose initial serum testosterone levels were more than 10 nM. Further imaging revealed a left adrenal adenoma. During an attempt at bilateral adrenal-ovarian venous sampling at another institution, her peripheral serum total testosterone levels on a different assay platform were surprisingly normal. Subsequently, simultaneous samples performed on three different assay platforms confirmed the presence of assay interference from the originating institution.
Testosterone

INTRODUCTIONSubclinical hyperthyroidism (SH, grade 1, thyrotropin (TSH) ≥0.1 mU/L and grade 2, TSH <0.1 mU/L) is a common disorder with increased prevalence in older subjects. There is evidence for increased morbidities in SH, such as atrial fibrillation and osteoporosis. We aim to study the natural history and comorbidities of SH from patients referred to a tertiary endocrine clinic in Singapore as they are currently unknown.

MATERIALS AND METHODSRetrospective evaluation of SH subjects for natural progression and comorbidities.

RESULTSOne hundred and thirteen SH subjects (male/female: 24/89, mean age: 67.2 years, grade 1/grade 2: 60/53) were identified from the endocrine clinic. The aetiology of SH include 52 multinodular goitre, 15 Graves' disease, 7 toxic adenoma and 39 unclassified. A minority of SH patients (5.3 %) progressed to overt hyperthyroidism while 13% remitted to euthyroid state (1 to 3 years with a mean follow-up of 18 months) in the total cohort. Most of the patients remained in SH state during follow-up (50/60 in grade 1 SH and 42/53 in grade SH). However, no single predictive factor could be identified for progression or remission of SH. The prevalence of morbidities in SH subjects include ischaemic heart disease (16.8%), heart failure (8.9%), tachyarrhythmias (13.3%), any cardiovascular disease (28%), cerebrovascular disease (28%), osteoporosis (28%), and any fracture (15.9%).

CONCLUSIONMost of SH cases in our cohort remain in subclinical state with very few progressing to overt hyperthyroidism. Significant proportion of SH subjects have vascular disease, but this association needs to be confirmed in prospective controlled studies.

Aged ; Disease Progression ; Female ; Humans ; Hyperthyroidism ; complications ; diagnosis ; Male ; Prospective Studies ; Tertiary Care Centers