Gout, with a section on ocular disease in the gouty

by Llewellyn J. Llewellyn

The Acute Paroxysm.—Garrod, it will be recalled, claimed that during an acute attack of gout the excretion of uric acid was diminished, and that coincidently therewith the uric acid blood content rose. But these findings in the blood and urine, which constituted the basis of his hypothesis that gout was due to renal inadequacy, have, as previously noted, been categorically disproved.

Turning to the more modern findings upon which such refutation of Garrod’s view was achieved, one point emerges that appears to favour the assumption of renal block. It is that, one or two days prior to an acute attack, an appreciable decline in the output of uric acid occurs.

But this, be it noted, is neither so marked nor so constant as the subsequent increase; in short, at the zenith of an acute attack, an augmented output of uric acid ensues. At the very time when presumably the alleged functional renal impediment would be most pronounced, the impermeability of the organs for uric acid accentuated! Surely such behaviour seems scarcely compatible with the supposition that there is even a temporary diminution in the capacity of the kidney to excrete uric acid. Does it not in truth constitute strong proof of the reverse? Moreover, the said vagaries that herald the oncoming and that chequer the course of the paroxysm are not invariable, an obvious caveat against hasty etiological inferences therefrom. Any tendency thereto should also be curbed by the reflection that, viewing the character of the uric acid excretion in gout as a whole, the variations therein are not more extensive than in healthy individuals, and assuredly, on the mere basis of the fluctuations in uric acid excretion, no diagnosis of gout is possible.

Retarded Purin Elimination.—The mainstay in argument, however, as advanced by more modern advocates of the renal theory of gout, is that a retarded output of exogenous purin is typical of this disorder; but, here, again, there is no room for dogmatism. Thus Walker Hall reminds us that “the quantity of purins present in the food does not overstep the solubility of urates in the blood-stream, for once the material is metabolised and ready for removal the amount of blood, so far as solubility goes, places the whole amount of purins within the reach of the renal cells in less than twenty-five minutes.” We see, therefore, as far as rapidity of transport to the kidneys is concerned, there is no delay in presentation of the opportunity for the excretion of exogenous purin. While the alleged tardiness of output is attributed to defective action of the kidneys, it is at least equally possible that the delay, as Walker Hall states, “may be due to a defective or idiosyncratic nuclear metabolism, which results in the formation of isomeric purins or incomplete purin combination, and which makes greater demands upon the selective activities of the renal cells;” for it must be recollected that as yet we are ignorant as to the exact form in which uric acid circulates in the blood-stream, whether as sodium mono-urate or in organic combination.

Moreover, experimental injections of uric acid into the tissues or veins show no impairment in the elimination capacity of the kidneys for uric acid. Thus, Wells cites evidence that “the kidney in gout shows no lack of ability to excrete uric acid injected into the tissues.”

Again, given intravenous injection of uric acid into a normal man, its excretion occupies several days, and it fails to appear quantitatively in the urine. But if administered during a course of atophan, then the whole amount injected is excreted within twenty-four hours. If the same procedure be followed in a gouty individual, precisely the same results are obtained; in other words, both normal and gouty kidneys react in identical fashion to atophan. Given an inherent functional defect, quâ uric acid excretion, in the gouty kidney, one would scarcely expect a wholly normal reaction thereto. Surely some disparity would be disclosed, some aberration in response as compared with normal renal organs.

Again, while McLester and others claim that atophan exerts “a selective stimulating influence on uric acid excretion,” it is quite possible that its rôle may be otherwise explained. May it not influence the actual formation of uric acid, or, failing this, the form in which it is presented to the kidneys for excretion? Nicolaier and Dohrn, indeed, believe that atophan influences in some way purin metabolism within the muscles and so leads to increased formation and excretion of uric acid. At any rate, whatever be the explanation of the action of atophan, the fact that healthy and gouty kidneys react alike thereto cannot be interpreted as proof of defective capacity for uric acid elimination in gouty subjects, indeed the reverse.

Moreover, in all our attempts to saddle the kidneys with the responsibility for the delay in exogenous purin excretion, we are for ever hampered in that we know not whether the alleged renal impairment is primary or secondary to the gout. That the kidneys are frequently functionally inefficient in the later stages of gout may be conceded. But what of the initial phases of the disorder? Some talk very glibly of subjects who are, they say, “potentially gouty.” But has the rate of disposal of ingested purins been investigated in persons suffering from so-called “goutiness,” or, perhaps more pertinently, in those individuals, not uncommon, who, while exhibiting auricular tophi, have yet experienced no frank attack of gout?

In this connection we may note that McClure has recently emphasised the fact that the kidneys, in the later stages of gout, are often functionally deficient, and that, accordingly, the faulty elimination of exogenous uric acid by gouty persons may be simply the result of such functional renal depression; in other words, not due to gout, but to the secondary or associated renal deficiency. Hence, having regard to the frequency with which renal inefficiency is met with in gout of any standing, he is inclined to discount the value of studies of exogenous uric acid elimination as an aid to the diagnosis of gout. Consequently, he holds that before the diagnostic status of retarded purin elimination, as a symptom of gout, can be established, an investigation of the output of uric acid in the different types of nephritis is essential.