1293

in the uncle be significant?1O Perhaps none of these factors arerelated to the tumour.A search for a history of maternal alcohol consumption dur-

ing pregnancy in children and young adults with cancer maybe helpful.University Affiliated Cincinnati

Center for Developmental Disorders,University of Cincinnati Department,

of Pediatrics,and Division of Hematology,

Department of Pediatrics,University of Cincinnati,Cincinnati, Ohio 45229, U.S.A.

LUSIA HORNSTEINCAROL CROWERALPH GRUPPO

EARLY DIAGNOSIS OF ANKYLOSING SPONDYLITIS

SIR,-Your editorial (Sept. 17, p. 591) notes the character-istic features of the pain of ankylosing spondylitis: insidiousonset, persistence for 3 months, morning stiffness, relief withexercise, and age under 40. Indeed, in our controlled study’ weshowed that reliance on these five historical features (selectedfrom seventeen questions) were sensitive (95%) and specific(85%) in the differential diagnosis of 138 patients with backpain attending the Stanford University rheumatology clinic.

Nevertheless, a minority of patients with definite ankylosingspondylitis2 may have other less discriminatory symptoms thatcan suggest mechanical spinal disease. In our study, 17% of 42patients claimed that the disorder was "caused by an injury",29% complained of dysaesthesiae in a lower limb, and 41% hadpain radiating below the knee. However, features such as theseshould not deter the physician from an early diagnosis of anky-losing spondylitis, when the other four or five more discrimina-tory findings are present.A radiograph is diagnostic, and, as you suggest, indis-

criminate use of HLA B27 typing is to be avoided.

Department of Medicine,Stanford University School of Medicine,Stanford, California 94305, U.S.A. ANDREI CALIN

WHAT IS NORMAL SERUM MAGNESIUM ANDPHOSPHATE?

SIR,-That the serum-T4 values reported by Dr MacGregor(Nov. 26, p. 1129) were reported in rnmol/1 and not nmol/1 isnot too misleading. What is important, however, is that a ser-um-magnesium level of 0-85 mmol;1 should be interpreted aindicative of hypermagnesaemia, especially at a time whenthere is so much conflicting biochemical data relevant to treat-ment with lithium. Unless the reference range in Dr Mac-

Gregor’s laboratory differs appreciably from the usual refer-ence ranges for magnesium, the figure given for

serum-magnesium is normal. MacGregor also states that afterremoval of the parathyroid adenoma the serum-phosphatereturned to normal. Was not the preoperative figure (0.88mmol/1), itself normal? Of the concentrations given only theone for serum-calcium can be considered abnormal.

Biochemistry Department,Airedale General Hospital,Steeton,Keighley, West Yorkshire BD20 6TD C. SANDERSON

*** This letter has been shown to Dr MacGregor, whose replyfollows.-ED. L.

SIR,-Biochemical results are nowadays usually precise but,like prices, they sometimes become inflated. When our lithium-

10. Fraumeni, J. F., Miller, R. W. J. Pediat. 1967, 70, 129.1. Calin, A., Porta, J., Fries, J. F., Schurman, L. J. Am. med. Ass. 1977, 237,

2613.2. Bennett, P. H. J., Burch, T. A. Bull. rheum. Dis. 1967, 17, 453.

treated patient was investigated in 1975 the normal range ofthe serum-magnesium in our laboratory was 0.5-0-8 mmol;1.Lately, and without my knowledge, the upper limit of normalwas increased to 1.0 mmol/1. On this reckoning, therefore, theserum-magnesium was normal. Nearly a third of lithium-treated cases have, however, shown hypermagnesaemia.1 Thepatient had serum-phosphate levels of 0.30 and 0-35 mmol/1when her serum-calcium was 3.1 and 3.17 mmol/1, before herparathyroid adenoma was excised. The substitution of "m" for"n" in the serum-T4 results was the result of human frailty.St. Luke’s Hospital,Guildford, Surrey GU1 3NT GERALD A. MACGREGOR

1. Christiansen, C., Baastrup, P. C., Transbøl, I. Lancet, 1976, ii, 969.

Commentary from Westminster

From Our Parliamentary Correspondent

The Health Tax on CigarettesTHE Government’s proposal for a cigarette health tax,

announced earlier this year by Mr David Ennals, Secre-tary of State for Social Services, is facing strong opposi-tion both in Brussels and at Westminster. Hopes that thetax would be settled by now have proved optimistic, anda decision this year now depends on a Ministerial meet-ing in Brussels next week. But further delay is not beingruled out. The proposal is that Britain should be allowedto impose a supplementary health tax on those cigaretteswith the highest tar yield, covering about 20% of themarket. The result would be a 7p increase on a packetof 20 plain cigarettes. But the plan is being resisted inBrussels where a meeting last week failed to reach anyconclusion. The European Commission is said not to likethe proposal and very few of our European partnershave advanced to such a stage in policy thinking oncigarettes and health. France and Italy both have Statemonopoly tobacco industries, which present them withparticular problems on taxation matters. Now Holland isasking why Britain alone should be given a special dero-gation to introduce such a tax. The Dutch want to seea general dispensation for every country.

At Westminster a number of M.P.S have stronglyattacked the idea of bringing the health element intotaxation. One Conservative has declared that healthmatters are not something which should concern theE.E.C.-although an examination of the Register ofM.P.s’ Interests reveals that he is an adviser to BritishAmerican Tobacco. Other M.P.s with more conspicuousconstituency interests in the tobacco industry have criti-cised the tax for the same reason. They see it as a threatto the industry, its 33 000 employees, the £2250 milliona year taxation it pays the Exchequer, and the ,200 mil-lion worth of cigarettes it exports every year. For theseM.P.s the main consideration is the need to protect theBritish industry. What is now concerning them is thatin pressing for a health tax, the British Governmentmight be persuaded to concede too much in the negotia-tions on the second stage of harmonising E.E.C. exciseduties. The first stage of this harmonisation comes intoeffect on Jan. 1 and involves changes in the pricingstructure which will put up the price of a packet of small