Constipation.
—Constipation is a well-known precursor of colic in lead poisoning cases, but is by no means an invariable rule. About 15 per cent. of cases of lead colic suffer from intermittent diarrhœa.
A number of cases (see the table on [p. 49]) show that “rheumatic” symptoms are amongst those associated with lead poisoning. Some of these rheumatic symptoms, as has been explained, may be due to minute hæmorrhages, in the muscle or elsewhere, setting up the pains of a rheumatic nature in the part affected. One other symptom occurs with considerable frequency both as a precursor of colic and as an associated symptom in constipation, and even in diarrhœa associated with lead poisoning, and often regarded as of rheumatic origin—namely, lumbago. Complaints of lumbago in lead-workers should always be regarded seriously, as they may be a guide in discovering an early intoxication.
From what has been said of the excretion of lead into the large intestine in poisoned animals, the symptom of lumbago often complained of by lead-workers may, in some instances at any rate, owe its origin to overloading of the large intestine, due to the inhibitory action of lead on the intestinal muscles. It has been seen that excretion of lead into the large intestine is the normal method of excretion of the metal, and that concomitant congestion of the vessels in the corresponding mesenteric area is an associated symptom in poisoned animals. Local vasomotor spasm may also contribute.
The Pulse.
—The pulse in lead poisoning in the incipient stage is perhaps not so important as when poisoning has become pronounced. Considerable variation exists amongst different observers with regard to the blood-pressure of lead-workers. Our experience is, on the whole, that it tends to be high, and pressures of 150 to 170 mm. Hg are common. In an average of 100 cases we found the highest pressure to be 178, and the lowest 115, the mean 150.
Collis[2], in a special report on smelting of materials containing lead, gives the average blood-pressure of 141 smelters as 148·2, and of 38 white lead-workers as 156·5.
Increase of tension undoubtedly takes place as lead absorption becomes more established, and the well-known high arterial tension of arterio-sclerosis is to be found in most workers employed in lead for any considerable period. Even in the cases quoted above showing no signs of lead poisoning, notwithstanding long duration of employment in lead factories, there was a distinct increase of arterial tension, not necessarily attributable to lead alone, but possibly also to such incidental causes as gout, alcoholism, syphilis, etc. When colic is present, marked diminution in the pulse-rate may be noticed during the spasms, and even without the presence of colic a diminution in the pulse-rate, with a definite increase of tension, as estimated by the finger, is a matter of practical importance in the diagnosis of absorption.
In quite early stages the pulse may be increased, and a small, rapid pulse should be regarded as a suspicious sign. Only in the later stages of the disease do alterations in the heart-sounds take place.
Sphygmograph tracings of the pulse of lead-poisoned persons shows the well-marked high tension type.