It would be useful to ascertain whether or not the "new" sphygmanometer being compared with the Omron HEM 711(1) was an aneroid device, given the fact that those of us who lamented what we perceived to be an ill advised rejection of the mercury device welcomed the prospect that aneriod sphygmanometers "may replace the traditional mercury column in the healthcare workplace"(2). In the latter study, there were no significant differences(using the paired t-test) between the mercury standard and the aneroid device(Baum & Co), but the oscillometric device(Omron HEM-907)significantly(p=0.002) overestimated the systolic blood pressure(SBP) and significantly(p=0.0002) underestimated the diastolic blood pressure(DBP)(2). A later study study compared the Welch Allyn Tycos 767-Series Mobile aneroid sphygmanometer with the mercury device, and found no statistically significant difference for SBP but a significantly(p < 0.0001) lower reading for DBP using the aneroid device(3). Oscillometric devices, on the other hand, have proved to be almost universally unreliable. In one study, an evaluation of 9 devices showed that "accuracy appeared to deccrease at increasing blood pressure levels" with the potential consequence that "in treated hypertensive patients the necessary adaptation of treatment will not take place"(4). More recently, a comparison was made between the professional oscillometric device BpTRU, that had achieved an A grade of the British Hypertension Society validation protocol for both SBP and DBP measurement, and the standard mercury sphygmanometer(Baumanometer; WA Baum Co). A total of 5070 BP measurements were made using the two devices simultaneously. Unreliable readings(ie > 10 mm Hg difference in either SBP or DBP) were found in 755 patients. Unreliable readings occured in 15% of systolic and 6.4% of diastolic blood pressures(5). In view of the fact that "A decreasing arm circumference was a significant predictor of persistent UOBP(unreliable oscillometric BP)"(5), this observation might signify that oscillometric devices might be inherently unreliable in children References (1) Midgley PC., Wardhaugh B., Macfarlane C., Magowan R., Kelnar CJH Blood pressure in children 4-8 years: comparison of Omron HEM 711 and sphygmanometer blood pressure measurements Arch Dis Child 2009;94:955-8 (2)Elliot WJ., Young PE., DeVivo L., Feldstein J., Black HR A comparison of two sphygmanometers that may replace the traditional mercury column in the healthcare workplace Blood Pressure Monit 2007;12:23-8 (3) Ma Y., Temprosa M., Fowler S et al Evaluating the accuracy of an aneroid sphygmanometer in a clinical trial setting Am J Hypertens 2009;22:263-6 (4) Braam RL., Thien T Is the accuracy of blood pressure measuring devices underestimated at increasing blood pressure levels? Blood Pressure Monitoring 2005;10:183-9 (5)Stergiou GS., Lourida p., Tzamouranis D., Baibas NM Unreliable oscillometric blood pressure measurement;prvalence, repeatability and characteristics of the phenomenon J Human Hypertension 2009;23:794-800

The question on how to manage the presence of the pandemic virus A/H1N1 in schools when the specific vaccine is not yet available is still open. Some countries have decided to postpone the opening of schools to avoid the epidemic peak, others have preferred to wait for the mass vaccination to contain the epidemic. WHO has recently issued a briefing note in which measures to be taken in school activities to limit the spread of virus A/H1N1 are detailed (1). In our experience, the education of students towards good hygiene practices has given interesting results. We are two recently graduated italian doctors who, in the period 6-21 July 2009, were accompanying - as a medical staff - an Italian group staying in Birmingham, composed by 163 students and 24 staff members. During this period, 7447 confirmed flu cases were notified in the UK(2), stating that this was an epidemic period for the new A/H1N1 virus. To avoid the contagion and its spread, some actions were taken in the small community: 1. Informing and educating all the guests, students and staff, on which good hygienic practices could help; 2. Distributing in strategic locations (toilets, meeting places) dispensers of antiseptic gel, to be used every time people had to shake hands, to touch objects, to eat or drink or after coughing e sneezing; 3. Stopping sport activities in the pool; 4. Isolating those with fever over 38°C, accompanied by flu-like symptoms, until the disappearance of symptoms. 5. Asking the intervention of NHS medical doctors authorized to prescribe antiviral drugs in every case of suspected flu. After adopting such measures, among the 187 Italian guests only 3 subjects had fever over 38°C and flu compatible symptoms within 7 days from arrival to the college, but only one was confirmed with swine-origin influenza A/H1N1 according to the protocol (3). Back in Italy, one additional girl had flu-like symptoms, and was subjected to laboratory tests which confirmed the presence of swine-flu infection. The application of preventive measures involved the consumption of 70 dispensers of antiseptic gel (18.7 mL/person/day). While our group was free to come back to Italy at the end of the programmed period, another group of 70 students had to be withheld for several days in the UK because 26 of them, in absence of hygienic prevention, fell down with flu in few days.

THE TSH THRESHOLD IN NEONATAL SCREENING FOR CONGENITAL HYPOTHYROIDISM: A VARIABLE SOLUTION

Dear Editor:

In their paper on the TSH threshold in neonatal screening for congenital hypothyroidism (CH), Korada et al. (1) conclude that a threshold of 6 mIU/L for DELFIA-measured TSH in samples collected between days 5 and 8 may be preferable to the 10 mIU/L recommended by the UK Newborn Screening Programme Centre. Our laboratory instituted DELFIA measurements of TSH in 5-8—day paper-borne heelprick samples in 1985. Since 1998 we have used an accelerated AutoDELFIA(R); method – fully endorsed by the results of external quality control services (DGKL, NEQAS, AECNE) – that takes about 2 h and thus allows follow-up samples to be called for, if necessary, on the same day as the first sample is analysed. Since 2003, heelprick has been performed on day 3 in response to the desire of paediatric endocrinologists to begin the treatment of CH patients as early as possible, even though the typical physiological TSH peak on day 2 reduces the efficiency of screening thresholds; Table 1 summarizes the distribution of TSH levels in the 102,789 newborns screened during this period.

Having observed significant between-lot variation in TSH assay kits, since November 2004 we recalculate our TSH threshold for every run in the light of two factors: a) the dispersion of the calibration data in the vicinity of 10 mIU/L; and b) measurements of certified control samples with concentrations close to 10 mIU/L that are supplied by Perkin Elmer and, within its Newborn Screening Quality Assurance Program, by the CDC. Defining CV10 as the coefficient of variation of two replicate fluorescence measurements of the calibration standard nearest to 10 mIU/L, expressed as a percentage, factor (a) is assigned the value zero if CV10 < 10, and the value 0.1 x CV10 otherwise. The control samples (C1 and C2, of certified concentrations c1 and c2, respectively) are each measured once; in each case a parameter bi (i = 1,2) is assigned the value zero if the measured value mi is greater than 90% of the certified value, or the value 10 x (ci – mi)/ci otherwise; and the value of factor (b) is defined as the greater of b1 and b2. Finally, the TSH threshold is defined as (10 – j) mIU/L, where j is the larger of factors (a) and (b). This entirely empirical algorithm is displayed in flow-chart form in Fig. 1. In the 1171 runs in which the above procedure has been followed, the threshold so determined was > 9 mIU/L in 54.7%, 8 9 mIU/L in 35.3%, 7-8 mIU/L in 8.5%, and < 7 mIU/L in 1.5%. Of the 62 cases of CH that we have detected in this time, three (all with adequate weight at birth) had first-sample TSH levels lower than 10 mIU/L (see Table 2 for details).

Cristobal Colon and Jose Ramon Alonso-Fernandez. Metabolopathy Laboratory, Departament of Paediatrics, Clinical Hospital and Universiy of Santiago de Compostela (Spain).

References 1) KORADA SM, PEARCE M, PLATT MPW, AVIS E, TURNER S, WASTEL H, CHEETHAM T. Dificulties in selecting an appropriate Neonatal TSH screening threshold. Arch Dis Child (Online First), 12 Aug 2009. 2) ALONSO-FERNANDEZ JR. V Reunion Nacional de la Sociedad Española de Química Clínica. Santiago de Compostela 28 y 29 de abril de 1985. 3) POMBO M, ALONSO-FERNANDEZ JR, BRAVO M, FRAGA JM, PEÑA J. Diagnostico Precoz del Hipotiroidismo Congénito y de la deficiencia de Hormona del Crecimiento. An Esp Ped. 1987;27(sup.28):44-47. 4) COLON C, ALONSO-FERNANDEZ JR. Depistage de L’Hipothiroidie neonatal avec un inmuno-essai marque a l’Europeum. Etude comparative de curbes de calibrage. Proceedings of “Reunion Europeene sur le Depistage Neonatal en 1986. Evian (France). 28-30 de abril de 1986. 5) ALONSO-FERNANDEZ JR, COLON C, FRAGA JM. Neonatal Screening of Hipotiroidism: A comparative study of RIA Technique and the Non Isotopic Inmunoessay DELFIA System. In BL Therrel; Advances in Neonatal Screening pp 163-164 (1987). Excerpta Medica. 6) COLON C, ALONSO-FERNANDEZ JR, CASTIÑEIRAS DE, ROMERO ME, FRAGA JM, PEÑA J. Posible Causes of Bordeline TSH: a Summary of our experrience. In F Delange, DA Ficher, D Glinder; Research in congenital Hypothyroidism, pp 316, 1989. Plenum Press. 7) COLON C.Epidemiological study of thyroid stimulating hormone (TSH) levels in the Galician neonatal population (Estudio epidemiologico de los niveles de hormona estimuladora del tiroides (TSH) en la poblacion neonatal gallega). Microfiche ISBN 13: 978-84-8121-340-9. ISBN 10:84-8121- 340-3. Ed. Universidade de Santiago de Compostela. 1995. 8) ALONSO-FERNANDEZ JR, CASTIÑEIRAS DE, CASTIÑEIRAS C, VILLAR P. Determinacion de TSH Neonatal con el método DELFIA reduciendo a dos horas el periodo de Elucion-Incubacion, concentrando el trazador y el analito. Immunoensayo 97. La Habana (Cuba) 14-18 de septiembre de 1997.

Post date

In 1985 (2, 3) we propound the adaptation of DELFIA test for seric TSH measurement to the newborn screening sample (DBS). Once Perkin-Elmer marketed the neonatal screening TSH test, we suggested a calibrate modification, increasing from 3 to 5 points and using the interpolation with logarithmic spline instead linear regression such as made in the procedure for seric and neonatal screening TSH determination (4). It is compared with the RIA test using until then (5). In 1988 we discussed the causes of borderline results (6), one of the main reasons for recall sample. In the PhD thesis of one of us (C. Colon) in 1995 (7), we could verify that the gestational age, the birth weight, and the age of analysis, influence on the TSH values. Also was found the thyroid function alteration due to antiseptic iodine use (effect Wolff-Chaikoff).

In 1997 we presented (8) a new DELFIA test for neonatal TSH modification; reducing until 2 hours the elution-incubation time, using half buffer volume in the preparation of tracer solution and reducing to 100 microlitres the volume of this solution dispensed in the microtiter plate wells containing the DBS disc. In the next year, using the AutoDELFIA, we introduced another modification, increasing to double the content of second antibody-tracer in the immunochemistry reaction mixture, in this mixture the analyte concentration result is multiplied for 2 and Europium-labelled antibody for 4.

In the “Images in Paediatrics” section of ADC, Sept 2009 (1), I read with interest, and some alarm, Sheth et al.’s assertion that CT scan findings were of “significant value” in establishing the diagnosis of Hirschsprung’s associated enterocolitis.

As the authors themselves point out, diagnosis of enterocolitis in a child with a history of endorectal pull-through operation for Hirschsprung’s disease should be made on clinical grounds, with a plain abdominal X-ray being the investigation of choice, if required. Although it appears from the clinical history that the authors give that the CT scan was performed on their patient in order to rule out intussusception - a very reasonable intervention in the circumstances– the conclusion that the authors draw in proclaiming CT scan findings to be of significant value in establishing the diagnosis of enterocolitis surely cannot be justified. In the case they describe, the CT scan was useful in ruling out diagnosis of intussusception, not in confirming the diagnosis of enterocolitis. The message from the article may be misinterpreted by practitioners who are less clinically astute than the authors as a recommendation to use CT scan, with all its inherent risks and side- effects, as a diagnostic tool of “significant value” in children with known Hirschsprung’s disease presenting in this way.

As a general paediatrician coming across such patients in the acute setting in my practice, I would be loathe to subject my patients to the radiation, not to mention the likelihood of sedation or anaesthesia, of a CT scan which does not influence my diagnosis or management. In my non- prefessional capacity, as the parent of a 13-month old infant with Hirschsprung’s disease who has been admitted on several occasions with suspected Hirschsprung’s associated enterocolitis, I would be even more loathe to consent to such an investigation for the indications the authors seem to suggest.

References 1. Sheth et al Images in Paediatrics “CT images of Hirschsprung’s associated enterocolitis: a rare finding. ADC 2009; 94: 816

Competing Interests: None