Document q2pQLn19ZM81ra30YBV6e5En

Th e Ch il d r e n 's Ho s p it a l Re s e a r c h Fo u n d a t io n C I N C 1 N N ATI, OHIO TDbc g l Ter CO, DEPARTMENT OF' PEDIATRICS COLLEGE OF MEDICINE UNIVERSITY OF CINCINNATI T r. T c h - r t Teho e, hetiering Laco ratcry, Medical College, Tder. and Lethe, sar. .-res Cincinnati, Ohio. -car -o, In the next edition of ny "book I :-ro-;lo line to scy the follovir-r if it is correct: "It 1: prolaLio that vnines of no re than 50 rr.icrcrnillirm.ns of lend per liter of '.rrir.e and .nore than ?4 mi crcmilligrri ' - C par ICO ce. of "blood indicate lead 'noioonirg; sorco nc'cld hold that loner figrros verc 3 inn:ficant, loc d in the tin: can o.lso ho determined srcctrographicall;;". ". The reference which I had for this \;nr- Ilchoe, J.d.M.A. , 1C': 134 21. Mould ;gon he good enorgh to tell no v;hether this is correct and whether there is a 'bettor reference vhich I right rive? ""hands `bofcrrha.nc, and Many Christmas. N13149 00.12433 December 27, 1939 Dr* A, Graeme Mitchell `The Childrens a Hospital Research Foundation Cincinnati# Ohio Dear Graeme? I have looked in vain for the source of the statement attributed to me in your letter of December 20th. Someone has misquoted me and I cannot put my finger on whom it was. Mot that the figures are so much in error for they are not far from the mean values, but rather that I have exercised the greatest care lb not attributing unduly great significance to the analytical information on patients. In any case there is no such statement in my article in the J.A.M.A, or in any other paper which I have written. Perhaps I had better give you the facts and let you choose what you wish to say, and since there la no publication which gives these facts' in ay name, (there is an article in press which gives part of it) you can best refer to my statement as a personal communication. If this does not suit you,let me know and 1*11 give you such references as I can, The normal values for the human blood have been obtained for the most part on adults, although in our experience there Is little difference in the case of ohildren after the change from an all-rallk diet. These values range from 10 to 50 ralcromilllgrams per 100 grama of whole blood, with rare values up to SO micromill1grams per 100 grams. The mean approximates 30 micromllligrams per 100 grama of whole blood. The range of normal values ia Just as important as the mean value and should be noted in all oas^a, in my opinion. Abnormal values range from the normal up to 400 mloromilligrams per 100 grams, dependent upon the extent of absorption of lead compounds. Any value in excess of oO micromilligrams per 100 grams of whole blood Is definitely abnormal if the technique of handling samples is sufficiently rigid. Such concentrations of lead may or may hot be associated with symptoms of intoxication, and are properly to be regarded as an evidence of increased lead absorption but not necessarily of lead Intoxication, The higher the lead concentration, the more probable it is that intoxication i3 actually present. There is, however, no definite level of lead concentration which. In and of itself, can be said to demonstrate the existence of lead 0012434 N13149.01 -2- Intoxication*. We have seen severe and fatal lead encephalopathy in children with from 200 to 300 micromilligrams of lead per 100 grams of whole blood. The normal range of urinary lead concentration la from 10 to 100 mioromilllgrama per liter, with a mean value of approximately 30 micromllllgrams per liter. Consistently maintained values in excess of 50 micromilligrams of lead per liter of urine In an Individual, (numerous repeated analyses) are indicative of abnormal lead Intake from some source, but are not hygienically or diagnostically sig nificant unless they are in excess of 100 microniilllgrams per liter, Values in excess of 150 raioromilligrams of blood per liter are suggestive of plumbism but are not necessarily associated v:ith symptoms or signs of illness. Here, again, elevated values mean only that abnormal lead absorption has occurred, and the higher the elevation, the greater the absorption. To summarise, briefly, lead con centrations in excess of 2k) micromilligraas per 100 grams of whole blood and in excess of 100 micromllllgrams per liter of urine, when demonstrated b& analytical methods of high accuracy comparable to ours, are indicative of recent abnormal lead exposure and absorption, and are compatible with the diagnosis of lead intoxication. The higher these values run, the greater has been the absorption of lead and the greater is their diagnostic significance. One should make the diagnosis fromthe clinical picture, however, employing the analytical data as evidence only of the occurrence and severity of the lead exposure. As to analytical methods, those which have demonstrated their adequacy for these purposes have made use either of the spectrograph or of some modification of the "dlthisone* technique. X hope these paragraphs give you what you want. If not, let rae know. Faithfully, RAKfle Robert "a ICehoe, "M.D. HE 0012435