GLYCOSURIA AND HEREDITY

1077

GLYCOSURIA AND HEREDITY.

THE LANCET.

LONDON: SATURDAY, MAY 26, 1928.

THE presence of dextrose in the urine used to be

regarded as pathognomonic of diabetes mellitus, but30 years ago a case was described in which glycosuriawas associated with nephritis, and the amount of

.sugar in the blood was normal. The next few years

.saw occasional reports of other cases in which the

blood-sugar remained at its usual level while dextrosewas being excreted by the kidney, and it was soonrealised that nephritis was but rarely associatedwith this phenomenon, and that, apart from this

finding, the patients were perfectly well. The

discovery by IVAR BANG that the blood-sugarcould be estimated accurately in small samples, andthe subsequent introduction of simpler methods, hasmade possible the careful study of many cases ofthis kind, and it is now clear that the sugar toleranceis quite normal. The reason why sugar appears inthe urine is that the " threshold " of the kidney isnot set at the usual level. Whilst a normal kidneydoes not begin to excrete dextrose until the blood-sugar has risen to 170-180 mg. per cent., the kidneysof these patients will do so at lower levels, the thres-hold being set at any point from the normal down to50 mg. or even lower. The condition may be suspectedwhen glycosuria is found unassociated with any ofthe usual symptoms of diabetes mellitus, and circum-stantial evidence can be got by studying the symp-toms which occur after a drastic reduction of carbo-hydrates in the diet or after injecting insulin. Adefinite diagnosis, however, can only be made afterobserving the effect of a dose of dextrose on the

blood-sugar, tests being made at half-hourly intervalsfor two hours.The condition thus discoverable has had various

names, such as renal diabetes, diabetes innocens, andnegligible glycosuria. In this country it is usuallycalled renal glycosuria, but the name of orthoglycæmic.glycosuria suggested by URBAN HJÄRNE in a recentmonographl is perhaps a better, because it signifiesthat the glycosuria occurs although the blood-sugaris normal; furthermore, it does not suggest any,disease of the kidney. Almost as soon as the condi-tion was recognised it was noticed that it oftenaffected more than one member of the same family,and it is this aspect of the subject that HaARNE hasbeen studying. Being lucky enough to find a familyin which it commonly occurs, he has made exhaustiveinquiries and observations. Seven generations havebeen studied, but nothing abnormal was discoveredin the history of the first three generations, whichcomprised ten known persons. In the fourth genera-tion there were 18 members of the family, and one hada glycosuria which did not run the course of a true-diabetes mellitus, and was probably orthoglycsemic.In the third generation there had been a marriage

1 Urban Hjärne : Acta Medica Scandinavica, 1927, lxvii.,422.

between first cousins, and in the fourth generation oneof the offspring of this marriage again married a cousin.It is therefore possible to divide members of the nextthree generations into three groups according towhether they sprang from two, one, or no first-cousinmarriages. The group in which there had been no

intermarriage consisted of 102 persons, 72 of whomwere examined. Of these, ten had either typicalorthoglycaemic glycosuria or had had a glycosuriawithout any symptoms of diabetes mellitus. Truediabetes occurred once in the fifth and once in theseventh generation, affording a striking contrast tothe other cases. The group which sprang from

one marriage between first cousins contained 108

persons, 77 of whom were examined. Fourteen ofthem had either an orthoglycæmic glycosuria or elsea glycosuria without any symptoms. One case oftrue diabetes developed in the fifth generation andone in the sixth. Lastly, in the third group, whicharose from two first-cousin marriages, there were41 persons, of whom 30 were examined. Of these2 out of 6 in the fifth, 8 out of 13 in the sixth, and6 out of 20 in the seventh generation had typicalorthoglycaemic glycosuria, as shown by sugar-tolerancetests, and there were no cases of true diabetes mellitus.This careful piece of work shows clearly that inter-marriage increases the frequency of this rare abnor-mality, and after investigating the family records,partly with a view to seeing whether the transmissionobeys the dominant or recessive laws of inheritance,HJÄRNE states that " the cases occur entirely inaccord with the manner and numbers in which amonofactorial dominant factor is inherited."For years there has been a difference of opinion

in this country between, on the one hand, those whorecognised that orthoglycæmic glycosuria was harm-less, and did not shorten life, and, on the other,most of the life assurance offices, who took the viewthat the condition had not been long enoughobserved for any such conclusion to be drawn.Acting on this opinion they have either refused

applicants altogether or loaded the policy againstthem in various ways. The evidence provided byHJÄRNE confirms the views of previous workers andshould go far towards inducing the life assuranceoffices to alter their attitude towards cases which,on proper investigation, prove to have orthoglycsemicglycosuria.

STATUS LYMPHATICUS.ABOUT 200 deaths are registered each year in this

country as due to " status lymphaticus." We owethe idea that there is an association betweenunexpected deaths from trivial causes and a bodilyconstitution characterised by a large thymus and ageneral excess of lymphoid tissue to PALTAUF, whoput it forward nearly 40 years ago, and there is stillsome doubt whether the expression really meansanything more than" G.O.K." In an admirablereview of the evidence published last year, Prof. M.GREENWOOD and Miss WOODS 1 came to the conclusionthat if " status lymphaticus " exists at all itsanatomical signs cannot be recognised post mortemand that therefore it cannot be regarded as a

satisfactory explanation of some of the deaths which"would in more pious, but not more superstitious,days have been attributed to the visitation of God."The committee appointed by the Pathological Societyof Great Britain and Ireland and the Medical ResearchCouncil came to much the same conclusion in their

1 Jour. Hygiene, 1927, xxvi., 305.