Thyroglobulin in serum as an indicator of iodine status during pregnancy

How to deal with dichotomous tests? Application of a rankit ordinal scale model with examples from the Nordic ordinal scale project on screening tests

OBJECTIVE

The purpose of this investigation was to improve a rankit ordinal model for evaluating and validating dichotomized tests in a prospective Nordic project.

MATERIAL AND METHODS

The model is based on the assumption that the S-shaped curve of fractions of positive for increasing concentrations can be de-convoluted to a histogram and thereby used to calculate the parameters for a ln-Gaussian distribution. In a Nordic survey, four urine samples with known concentrations of hCG (human chorionic gonadotrophin) and nitrites were distributed to more than 2500 practitioners' offices.

RESULTS

The results are presented as parameters (geometric mean and CV) for the components urine-hCG and urine-nitrites, together with fractions of positive for clinical critical values (5 and 40 IU/L for hCG), for which fractions should be below 0.01 and above 0.99, respectively, and 7 micromol/L for nitrites. Furthermore, the concentration intervals of varying fractions of positive from 0.01 to 0.99 are estimated as grey zones. The parameters and grey zones for different kits are compared. No urine-hCG kit fulfilled the low clinical criterion, whereas all fulfilled the high criterion. Seven of the eight nitrites kits had fractions of positive above 0.9 for the company confirmation limit, but varying fractions for the clinically important limit of 7 micromol/L (fractions from 0.06 to 0.83).

CONCLUSIONS

The present model makes it easy to estimate parameters for the kits, and also to estimate the fractions of measured positives for specified concentrations. It is thus suited for external quality assessment as well as for manufacturers' method validation.

Gestation-specific thyroxine and thyroid stimulating hormone levels in the United States and worldwide

BACKGROUND

Euthyroid women experience dramatic changes in the demand for thyroid hormone production as early as the first trimester of pregnancy. These changes are important for fetal neurodevelopment and organ development as well as maternal health and succesful full term pregnancy. Therefore, gestation-specific reference intervals assist in appropriate clinical management of thyroid disease in pregnancy to ensure maternal and fetal health.

OBJECTIVE

To determine trimester-specific levels of serum thyroxine (T4) and thyroid stimulating hormone (TSH) in the U.S. population based on the National Health and Nutrition Survey III and compare these with published trimester-specific T4 and TSH means and medians obtained in other countries worldwide.

METHODS

Trimester-specific means and medians for T4 and TSH were determined for the U.S. population based on the National Health and Nutrition Survey III database (1988-1994). These were compared with trimester-specific means and medians of other countries in the published literature.

RESULTS

Mean serum T4 levels for the U.S. population were 141.35, 152.95, and 142.65 nmol/L in the three trimesters, respectively, whereas mean serum TSH levels were 0.91, 1.03, and 1.32 mIU/L.

CONCLUSIONS

Gestation-specific mean T4 and TSH levels for the representative U.S. population are well within the trimester-specific reference intervals. T4 and TSH measured during pregnancy in longitudinal and cross-sectional studies of populations worldwide demonstrate that, in some populations, T4 and TSH levels are outside the normal trimester-specific reference intervals.

Clinical and bacteriological outcome of different doses and duration of pivmecillinam compared with placebo therapy of uncomplicated lower urinary tract infection in women: the LUTIW project

OBJECTIVE

To analyse associations between symptoms and bacteriuria in uncomplicated lower urinary tract infection in women (LUTIW) and to evaluate outcome of therapy with three different regimens of pivmecillinam or placebo.

DESIGN

Prospective, multicentre, randomized, double-blind, and placebo-controlled therapy study. Symptoms registered at inclusion, during therapy and at follow-up visits after 8-10 and 35-49 days. Significant bacteriuria defined according to current European guidelines.

SETTING

A total of 18 primary healthcare centres in northern Sweden. Subjects. Women aged 18 years and above with symptoms of urgency, dysuria, supra pubic or loin pain. Main outcome measures. Symptoms and bacteriuria at inclusion and course of symptoms, bacteriuria, and their combinations during and post-therapy.

RESULTS

At inclusion, no associations or significant differences were found between symptom scores and bacteriuria, bacterial counts, or species. The 884 patients (77%) with significant bacteriuria were followed up. All pivmecillinam therapies were superior to placebo (p < 0.001). From day six until first follow-up, the mean values of all symptoms were higher and the bacteriological cure was lower at first follow-up in the three days (84%) compared with the seven days regimens (93-94%, p < 0.001). At final follow-up clinical cure was similar in all pivmecillinam regimens (65-72%) as was bacteriological cure (83-89%). Pivmecillinam had few low to mild adverse reactions, comparable to placebo.

CONCLUSIONS

Symptoms are not conclusive for diagnosis of LUTIW. Pivmecillinam therapies are superior to placebo and seven days regimens are more efficient than three days. Pivmecillinam 200 mg x 2 x 7 days is recommended as a first-line therapy for LUTIW.

Comparison between 24-h proteinuria, urinary protein/creatinine ratio and dipstick test in patients with nephropathy: patterns of proteinuria in dipstick-negative patients

OBJECTIVE

Three main tests are commonly employed for the measurement of proteinuria: the dipstick test, the urinary protein/creatinine ratio (P/C) and the 24-h urine collection. The aim of this study was to evaluate the correlation between these methods, comparing linear regression and ROC curve data.

MATERIAL AND METHODS

A total of 297 consecutive outpatients with different renal diseases were included in the study. Twenty-four-hour proteinuria was considered the reference test.

RESULTS

A high degree of correlation was observed between all the tests (p<0.0001), the highest regression coefficient being between 24-h proteinuria and P/C (R=0.82), and the lowest between P/C and the dipstick test (R=0.72). The dipstick test failed to detect pathological proteinuria in 94 patients (31.6%). Therefore, in these subjects, the patterns of proteinuria were assessed by immunofixation and sodium dodecyl sulphate (SDS) electrophoresis.

CONCLUSIONS

Our data strongly support the use of urinary P/C for the detection of proteinuria, at least in nephrology units, where the prevalence of proteinuria is likely to be high.

Long-term environmental exposure to perchlorate through drinking water and thyroid function during pregnancy and the neonatal period

We have conducted a longitudinal epidemiologic study among pregnant women from three cities in northern Chile: Taltal with 114 microg/L, Chañaral with 6 microg/L, and Antofagasta with 0.5 microg/L perchlorate in the public drinking water. We tested the hypothesis that long-term exposure to perchlorate at these levels may cause a situation analogous to iodine deficiency, thus causing increases in thyrotropin (TSH) and thyroglobulin (Tg) levels and decreased levels of free thyroxine (FT4), in either the mother during the early stages of gestation or the neonate at birth, or in the fetus cause growth retardation. We found no increases in Tg or TSH and no decreases in FT4 among either the women during early pregnancy (16.1 +/- 4.1 weeks), late pregnancy (32.4 +/- 3.0 weeks), or the neonates at birth related to perchlorate in drinking water. Neonatal birth weight, length, and head circumference were not different among the three cities and were consistent with current U.S. norms. Therefore, perchlorate in drinking water at 114 microg/L did not cause changes in neonatal thyroid function or fetal growth retardation. Median urinary iodine among the entire cohort was 269 microg/L, intermediate between that of pregnant women in the United States at National Health and Nutrition Examination Survey (NHANES) I and at NHANES III and consistent with current World Health Organization (WHO) recommendations. Median breast milk iodine was not decreased in the cities with detectable perchlorate. Analysis of maternal urinary perchlorate excretion indicates an additional dietary source of perchlorate.

The clinical art and science of urine microscopy

PURPOSE OF REVIEW

The examination of urine sediment is a diagnostic test which is frequently neglected by nephrologists. With this review the authors wanted to demonstrate that it can provide useful and relevant information in a wide spectrum of clinical situations.

RECENT FINDINGS

The authors reviewed the main contributions dealing with urine sediment examination, published in international journals in the period from January 2002 to April 2003. After a section on methodological aspects, they described the importance of urine sediment examination in various diseases of the urinary tract. These included bladder B-lymphoma, systemic histoplasmosis, urate nephropathy, Fabry disease, myeloma cast nephropathy, giant cell arteritis, and lupus nephritis. The significance of 'decoy cells' in the urine as a marker of polyomavirus BK reactivation was also discussed, both in renal transplantation and other conditions such as solitary pancreas transplantation, chronic lymphatic leukaemia, and HIV infection. In the section devoted to urine sediment changes caused by drugs the authors dealt with leukocyturia induced by indinavir, and crystalluria, which can follow amoxycillin and acyclovir administration. Finally, they reported on the utility and limits of flow cytometry for the automated analysis of urine sediments.

SUMMARY

The review of the recent literature on urine sediment examination shows that this test has important clinical implications in a large spectrum of diseases. Therefore, it should be more widely used by nephrologists.

Clinical and biochemical characteristics and genotype-phenotype correlation in Finnish variegate porphyria patients

Variegate porphyria (VP) is an inherited metabolic disease resulting from the partial deficiency of protoporphyrinogen oxidase, the penultimate enzyme in the heme biosynthetic pathway. We have evaluated the clinical and biochemical outcome of 103 Finnish VP patients diagnosed between 1966 and 2001. Fifty-two per cent of patients had experienced clinical symptoms: 40% had photosensitivity, 27% acute attacks and 14% both manifestations. The proportion of patients with acute attacks has decreased dramatically from 38 to 14% in patients diagnosed before and after 1980, whereas the prevalence of skin symptoms had decreased only subtly from 45 to 34%. We have studied the correlation between PPOX genotype and clinical outcome of 90 patients with the three most common Finnish mutations I12T, R152C and 338G-->C. The patients with the I12T mutation experienced no photosensitivity and acute attacks were rare (8%). Therefore, the occurrence of photosensitivity was lower in the I12T group compared to the R152C group (P=0.001), whereas no significant differences between the R152C and 338G-->C groups could be observed. Biochemical abnormalities were significantly milder suggesting a milder form of the disease in patients with the I12T mutation. In all VP patients, normal excretion of protoporphyrin in faeces in adulthood predicted freedom from both skin symptoms and acute attacks. The most valuable test predicting an increased risk of symptoms was urinary coproporphyrin, but only a substantially increased excretion exceeding 1,000 nmol/day was associated with an increased risk of both skin symptoms and acute attacks. All patients with an excretion of more than 1,000 nmol/day experienced either skin symptoms, acute attacks, or both.

Identifying bacteria in human urine: current practice and the potential for rapid, near-patient diagnosis by sensing volatile organic compounds

Urinary tract infection (UTI) represents a significant burden for the National Health Service. Extensive research has been directed towards rapid detection of UTI in the last thirty years. A wide range of microbiological and chemical techniques are now available to identify and quantify bacteria in urine. However, there is a clear and present need for near, rapid, sensitive, reliable analytical methods, preferably with low-running costs, that could allow early detection of UTI and other diseases in urine. Here we review the "state of the art" of current practice for the detection of bacteria in urine and describe the advantages of the recent "e-nose" technology as a potential tool for rapid, near-patient diagnosis of UTI, by sensing volatile organic compounds (VOCs).

Thyroid function in the newborn in relation to maternal thyroid status during labour in a mild iodine deficiency endemic area in Sudan

OBJECTIVES

Data on neonatal and maternal thyroid function during labour in a mild iodine deficiency endemic area are lacking. The current study focuses on elucidating the thyroid function during labour, in a group of pregnant women who live in an area of mild iodine deficiency in Sudan compared to that observed in their corresponding newborns.

MEASUREMENTS

Serum concentrations of TSH, thyroglobulin (Tg), triiodothyronine (T3) and free thyroxine (FT4) were investigated during labour in a group of mothers and their neonates residing in an area with mild iodine deficiency in Sudan (n = 76 mother-newborn pairs).

DESIGN

Maternal blood samples were taken on two occasions: first, during the third trimester of pregnancy (weeks 32-39); and, second, just before delivery. Cord blood samples were obtained by a doctor or a trained midwife during delivery.

RESULTS

The median concentrations (and interquartile ranges) of neonatal TSH, Tg, T3 and FT4 were 6.8 (4.7-12.4) mU/l, 61 (40.2-98.2) microg/l, 0.9 (0.8-1.2) nmol/l and 14.2 (13.4-15.9) pmol/l, respectively. The corresponding levels for the mothers during labour were 2.3 (1.9-3.2) mU/l, 33 (15.0-56.8) microg/l, 2.6 (2.0-2.9) nmol/l and 11.4 (10.3-13.3) pmol/l, respectively. The median neonatal serum concentrations of TSH, Tg and FT4 were significantly higher than the corresponding maternal levels (P < 0.0001, P < 0.0001, P < 0.0001, respectively). In contrast, the median maternal serum concentration of T3 was significantly higher than that of the neonates (P < 0.0001). When the different neonatal thyroid parameters were compared with each other, significant correlations were observed between TSH and FT4 (r = 0.4, P = 0.001); Tg and T3 (r = -0.3, P = 0.04) and Tg and FT4 (r = 0.5, P = 0.0001). Women with Tg concentrations above 20 microg/l showed a higher median TSH concentration and lower median FT4 concentration than those with Tg concentrations below 20 microg/l (P < 0.001, P < 0.001, respectively). Nevertheless, the thyroid function of neonates born of mothers with elevated Tg was similar to that of neonates born of mothers with low Tg levels. No significant changes had occurred in the thyroid function parameters between the third trimester of pregnancy and during the time of labour. The thyroid function indicators of the babies born by vaginal delivery did not differ significantly from those of the babies born by Caesarian section.

CONCLUSIONS

The study suggests that, in areas with mild iodine deficiency, neonates may be at the limit of decompensation as evidenced by their enhanced TSH and Tg levels as well as increased T4 compared to their mothers. This finding must not create a false sense of well-being and points rather to the urgency of iodine supplementation of mothers even in areas with mild iodine deficiency, as in this part of Sudan. The mode of delivery, whether by spontaneous vaginal delivery or Caesarian section, did not seem to affect the thyroid function of the newborn.

Evaluation of Aution Max AX-4280 automated urine test-strip analyser

Aution Max AX-4280, an automated urine test-strip analyser, was evaluated in three centres. Method comparison, imprecision, carry-over, linearity, detection limit and drift studies were performed for glucose, protein, blood and leukocytes using Uriflet S 9UB strips. These strips enable measurement of pH, glucose, protein, blood, leukocytes, ketones, bilirubin, urobilinogen and nitrite. Specific gravity is determined by the refractive index method. Within-run and between-day imprecision, assessed using pooled urines and quality control materials, were good. No drift over 24 h or sample carry-over was observed. Method comparison with quantitative methods for glucose, protein and specific gravity yielded good correlations. Ascorbate negatively interfered with haemoglobin, glucose and nitrite measurements. Acetylsalicylic acid lowered pH, the effect being greatest when protein was absent. During the assessment period no malfunction or breakdown was reported. The Aution Max is easy to use and needs minimal maintenance.

Reference intervals for the markers of proteinuria with a standardised bed-rest collection of urine

Reference intervals for markers of proteinuria or glomerular charge selectivity were measured in 61 healthy female and 61 healthy male individuals. Timed bed-rest and daytime collections were used to assess significance of preanalytical variability of results. Bed-rest collections are advisable for research on renal damage, whereas in routine care, robust protein/creatinine ratios work as practical estimates of protein excretion rates, the correlations to excretion rates improving with increasing proteinuria. For glomerular charge selectivity, pancreatic/salivary isoamylase clearance ratio showed lower within-subject biological variation than IgG/IgG4 clearance ratio, allowing more accurate classification into normal and reduced charge selectivity. With our method, the lower 2.5% reference intervals for isoamylase clearance ratio were 1.1 in men and 1.9 in women.