492

In practice serum-phenytoin levels on outpatients do not

provide a reliable guide to management of therapy. Serial esti-mations on inpatients under controlled conditions may do so.If the patient shows clinical signs of phenytoin intoxication,serum levels may confirm this.

My own solution to the problems of phenytoin serum levelsand its wide variety of unpleasant side-effects is to stop usingthe drug and change to carbamazepine or sodium valproate.E.E.G. Department,Dudley Road Hospital,Birmingham B18 7QH

P. M. JEAVONS

INTENTIONAL RADIOIODINE ABLATION INGRAVES’ DISEASE

SIR,—In 1973 we embarked upon a programme of inten-tional radioiodine ablation for Graves’ disease, similar to thatof Wise et al.’ Our preliminary data showed a 98% eliminationof hyperthyroidism within three months.2 Our methods resem-bled those of Wise et al. in that we gave 8-12 mCi doses forsmall goitres, 15-20 mCi for intermediate goitres, and 30 mCifor large goitres. Patients were re-examined after one-and-a-half months, three months, and nine months, then annuallyunless more frequent evaluations were necessitated by individ-ual circumstances. We followed the progress of 151 patientsfor from one to three years. This experience with a geographi-cally different population, probably containing more patientswith large toxic diffuse goitres, provided data which partiallyaccord with and partially differ from those of Wise et al.

Hyperthyroidism was eliminated with a single treatmentwithin three months for 144 (95%) patients, and within sixmonths for the 7 patients who required two treatments. Withinsix months, 127 (84%) patients were taking replacementL-thyroxine to correct hypothyroidism z2 mg/dy)whereas 24 (16%) patients were euthyroid without supplement-ation. Our resulting higher number of euthyroid patients mayreflect the number of patients with larger goitres who were lesslikely to become hypothyroid even after large’3’I doses.3

Although the subsequent course of the patients of Wise et al.was characterised by stability of thyroid function, instabilitywas observed in many of our patients; 7 of 24 initially euthy-roid patients developed hypothyroidism one or more yearslater. Perhaps less familiar to many workers, and as yetobserved neither by Wise et al. nor by Safa and Skillern whoalso advocate routine large "’I doses, is the recovery of non-suppressible thyroid secretory activity after a variable periodof up to one year or more during which endogenous thyroidfunction is quiescent. Because of the additive effects of the exo-genous and endogenous hormone, manifestations of thyrotoxi-cosis may recur. 1-7 For this reason, the L-thyroxine dose hadto be reduced for 8 patients, and discontinued for 5.

Wise et al. allude to the risk of patient non-compliance, aproblem for 7 (5.5%) of our 127 initially hypothyroid patients.Since unrecognised hypothyroidism occurred in 12% of pa-tients treated with conventional 13 11 doses,* our rate of patientdereliction seems not to be excessive, although we must antici-pate a further increment in this complication with time. Weplan to implement the suggestion of Wise et al. that MedicAlert bracelets be provided for patients. We have given eachpatient a copy of a book written for the layman,9 and have

1. Wise, P. H., Ahmed, A., Burnet, R. R., Harding, P. E. Lancet, 1975, ii,1231.

2. Hamburger, J. I. Clinical Thyroidology; p. 86. Southfield, Michigan, 1974.3. Hamburger, J. I. Hyperthyroidism: Concept and Controversy; p. 100.

Springfield, Illinois, 1972.4. Safa, A. M., Skillern, P. G. Archs intern. Med. 1975, 135, 673.5. Meier, D. A., Hamburger, J. I. Mich. Med. 1970, 69.6. Hamburger, J. I. Hyperthyroidism: Concept and Controversy; p. 125.

Springfield, Illinois, 1972.7. Hamburger, J. I. Clinical Thyroidology; p. 87. Southfield, Michigan, 1974.8. Wise, P. H., Ahmad, A., Pain, R. W. Unpublished.9. Hamburger, J. I. Your Thyroid Gland: Fact and Fiction. Springfield,

Illinois, 1975.

reviewed with them the sections which deal with 131I therapyfor hyperthyroidism and the need for aftercare. We believe thishas been helpful.

Because intentionally ablative doses of 131I are cheap, easyto administer, and give a rapid response, we agree with Wiseet al. that this approach deserves wider consideration.

Associated Endocrinologists,Northland Thyroid Laboratory,Northland Medical Building,Suite 300,20905 Greenfield,Southfield,Michigan 48075, U.S.A. JOEL I. HAMBURGER

BLOOD-TRANSFUSION AND HEPATITIS

SIR,---Allen’ 1 claims that our remark that"Blood-transfusions play only a minor role in the spread ofhepatitis"2 is incorrect. However, this claim has been fairlywell documented: most cases of acute hepatitis appearingwithin a certain area during a certain period of time have nopast history of blood-transfusion. In Denmark, for instance,97-98% of all registered cases of acute hepatitis had no pasthistory of transfusion of blood or blood products.3 Similar experiences have been recorded elsewhere.4-8 Thus, epidemiolo-gically, there must be very important sources of hepatitis infec-tion besides blood-transfusion.Commenting on hepatitis related to hospital Allen cites his

study of post-transfusion hepatitis.9 However, investigationswhich lack strict comparability of study groups, unambiguousdiagnostic criteria for hepatitis, and adherence to a prospec-tive, blind technique cannot provide firm evidence on the rateof acute hepatitis in transfused and non-transfused hospitalnatients.

Mainz, GermanyA. ARNDT-HANSER

H. FIEDLERMünster, Germany G. MAASS

Zürich, Switzerland M. FREY-WETTSTEIN

Chicago, Illinois, U.S.A L. R. OVERBY

Copenhagen, Denmark V. REINICKE

Milan, Italy U. ROSSI

Leuven, Belgium C. VERMYLEN

’BACTERURITEST’ STRIPS

SIR Many microbiology laboratories in Britain follow

Leigh and Williams’Osemiquantitive method for urinary bac-terial counts, using ’Bacteruritest’ strips (Mast Laboratories)

Leigh and Williams used Postlip Mill 633 paper in their

original technique and proposed a colony-count of 25 or morefor bacilli and 30 or more for cocci as representing significantbacteriuria.11 They further suggested that if a different paperwere used it might be necessary to redraw the calibrationcurves. Mast Laboratories no longer use their original supplierof Postlip Mill 633 paper for their bacteruritest strips, andthere may be a possible difference in the quality of the paper.Users have not been informed of this change. The implicationof this change is that new calibration curves will have to bedrawn since the old ones may no longer be valid. In issue no,

1. Allen, J. G. Lancet, 1975, ii, 1039.2. Arndt-Hanser, A., Fiedler, H., Maass, G., Frey-Wettstein, M., Overby, L R.,

Reinicke, V., Rossi, U., Vermylen, C. ibid. p. 329.3. Reinicke, V. Scand. J. infect. Dis. 1974, 6, 285.4. Höpken, W., Willers, H. Immunbiol. Inform. Behring, 1975, 15, 161.5. Wolschlin, P., and others. Schweiz. med. Wschr. 1975, 105, 1307.6. Heathcote, J., Sherlock, S. Lancet, 1973, i, 1468.7. Fiedler, H. Vox. Sang. 1974, 26, 368.8. Eisenburg, J. Arzl. Prax. 1973, 25, 876.9. Allen, J. G. Epidemiology of Posttransfusion Hepatitis. Stanford, 1972.

10. Leigh, D. A., Williams, J. D. J. clin. Path. 1964, 17, 498.11. Kass, E. H. Trans. Ass. Am. Phyns. 1956, 69, 56.