Document X3Kq8K3VQGb9XdkOkB7VE4pd

1 February 8, 1938 Br . Kenneth Blackfan djhildren*s Ho s p it a l 300 Longwood Avenue Boston , Mass, : Bear Doctor Blackfan j ' ' -' In accordance with the ( r equest la your le t t e r o f February 2nd, I am sending ' you two papers from the la b o r a t o r y, one of which give s the d e t a ils of our d lt h lzo n e method and the other gives a r a t h e r d e t a ile d comparison o f the d it h lzo n e and the sp ec* tr ogr a p h ic methods, You w ill note from the la t t e r paper th at the r e s u lt s obtain ed from the two method are sub* s jt a n t ia llv the same. In fa c t the accu r acy of the method o f a n a ly s is is co n s id e r a b ly more than the accur acy o f our p h ysiological, in ter p r etation of the r e s u lt s , Th is, I b e lie v e , w ill ser ve t o answer your qu estion as to whether the use o f the dithlzone^ method has m odified my opinion as to the normal blood le v e ls . The figu r e s which I gave you in my le t t e r o f la s t June a r e , t h e r e fo r e , s u b s t a n t ia lly co r r e ct , I may say t h a t in some r e ce n t d ata on two e xp e r i mental s u b je ct s follow ed over a per iod of months under f0lra,ob0m3o2r 0am,t 0og1rsy, t opc oe0rn.d10i07t0,i o gnrTsa,hmistsh,eoXfmbbealeonloi erdev, sewu, lt ith fa in the var ia ir ly r blood tion s eprese was e xt e n d in nts the g normal range o f v a lu e s . Perhaps I should p oin t out t o you , however, th at i t is e a s ie r to r ecogn ise abnormal fin d in gs in the u r in e than i t is in the b lood . For example, we have r e ce n t ly st u d ied s e ve r a l groups of workmen in le a d tr ad es in which the lead exposure was r e la t iv e ly s $ a ll. Those groups could r e a d ily be d iffe r e n t ia t e d fr e e each other on the b a s is o f the u r in a r y fin d in g s , b u t one did not fin d a s ig n ific a n t s t a t is t i c a l d iffe r e n ce in the groups on the b a s is o f t h e ir mean blood le v e ls . To be s t i l l more s p e c ific , an per un10e0xpgorsaemd sgroofupblohoadd a mean blood and a u r in ar le a d y lev le el ve of l aboofu0t .0Q3.80I4.mmgsg,s, per lit e le a d r . le A very vel of 0*s 0li4g5h t ly ***& exposed group had & corresponding u r a in co r r ary es le pon vel d in g of 0b. 0lo8o, d The d iffe r e n ce s in the u r in a r y va lu e s were s t a t is t i c a lly s ig n ific a n t w hile the d iffe r e n ce s between the blood le v e ls were not s t a t is t i c a lly s ig n ific a n t , and th er efor e pr ovided no b a s is fo r d iffe r e n t ia t io n , As a m atter o f fa c t , we have found u n ifor m ly t h a t where u r in e samples can be co lle ct e d In such a way as to avoid any p ossible con tam in ation , they N2 1 2 3 8 r / 2 are more u s e fu l fo r d ia gn o s t ic purposes than any other type o f b io lo gic m a t e r ia l. I have always f e l t I t necessar y to be cau tiou s In the aoceptanoe of the d ia gn o s t ic s ign ifica n ce of any a n a ly t ica l r e s u lt s of a b or d er lin e t yp e . Thus, i f the blo o d fin d in gs are in excess of a ten th of a m illigr am per 1.00 grains o f b lo o d , on can be fa i r ly sure of s ig n ific a n t e xp o s u re . By the same t oke n , I f u r in a r y r e s u lt s are cor r e s pondingly h ig h , the in t e r p r e t a t io n is not d i ffi c u l t . My o nly p oin t is t h a t the u r in a r y r e s u lt s in a given case ar e more lik e ly to be d e fin it e ly abnormal than ar e the blood fin d in g s , I am not q u ite ce r t a in as to the p h ys io lo gic in t e r p r e t a t io n o f th l3 fa c t , but that i t is a fa c t is without doubt, I p er son ally l i k e to have both blood samples and u r in e samples fo r a n a lys is In most ca s e s , and in some in s t a n ce s , e s p e cia lly those with r e c e n t exp osu r e, I lik e t o have fe c a l samples a ls o . The la t t e r a r e , o f co u r se , the le a s t u s e fu l in most cases sin ce i t is very d iffic u lt to in ter p r et the r e s u lt s of a sin gle fe ca l an alysis on account of the extreme v a r ia b ilit y of tbs lead con ten t o f the food m a t e r ia l. In the case of cn ild r e n , however, on se ve r a l o cca s io n s a d iagn osis has been made p ossib le by the d iscove r y o f p ain t-cove r ed fragments o f wooden o b je ct s in thC s t o o l* In cid e n t a lly , befor e con clu d in g, I! should p oin t out th at in our e xp er ien ce , ther e is ver y l i t t le d iffer e n ce in the r a t e of lead excr etion of childr en as compared to a d u lt s , whether under normal con d ition s or under con d ition s o f lead exp osu r e, I am not prepared to soy t h a t tlfiis is always the ca s e , b u t so fa r we ar e n ot Ju s t ifie d in d iffe r e n t ia t in g ch ild r en from ad u lts with r esp e ct to r a t e of lead e xcr e t io n . Sin ce r ely yours. Ra Kiis Rober t A, Kehoe, fei.D, g 04440