The blood picture in lead poisoning has a peculiar significance from the standpoint of diagnosis. For, curiously enough, the diagnosis of this disease in its early stages is still uncertain despite the fact that poisoning by lead is foremost among the industrial diseases. In its acute or advanced chronic stages the characteristic pallor, the lead line in the gums, the colic, nephritis and wrist drop have become familiar even to the layman. But in the borderline cases, there appears to be no end of difficulty in establishing the diagnosis. Cases of lead colic are still being operated upon for appendicitis. From the standpoint of compensation, furthermore, the absence of anything which can be regarded as pathognomonic of this disease is constantly leading to considerable confusion, and frequently to serious in justice to the worker.
Stippling of the red blood cells, or basophilic degeneration was at one time regarded as pathognomonic of lead poisoning. Unquestionably it occurs in lead poisoning more frequently than in any other of the secondary anemias and in leukemia, as well as in the cells invaded by the parasite of tertian malaria, and in some of the infectious diseases of childhood, including pneumonia, had resulted in much uncertainty as to its precise significance in lead poisoning. This has been still further increased by the fact that an occasional stippled cell has been reported from time to time in normal blood. [A control series of 250 normal individuals was examined for stippling, only one case of stippling was found.
One must conclude from this that stippling is of sufficiently rare occurrence in normal blood to be practically negligible 0.4 of I per cent.] The result has been an unending discussion as to the frequency of occurrence of stippling in lead poisoning. The Sickness Insurance office at Leipzig, Germany, has taken the extreme position that the presence of stippled cells is the fundamental basis for compensation. It is alleged that the use of this standard has not merely made it possible to give assistance to persons in the early stages of the disease before irreparable damage has be done but that it has also of value in eliminating a good many cases which were erroneously diagnosed as lead poisoning.
The Bureau of Industrial Hygiene, as part of an intensive study of lead poisoning, made a very careful examination of the blood of 381 lead workers in the State of New York. This examination was not confined to a search for stippling, but included in addition both red and white cell counts; a haemoglobin determination; a differential count; and a careful examination of morphology of the cells.
Of the 381 lead workers examined, 238 or 62 per cent. showed one or more of the following blood changes, and in the following order of frequently.
Pallor of the red cells 71 percent.
Nucleated red cells 8.
Myelocytes (eosin) 2.
Any other abnormal cells 1.
It is interesting to note that stippling ranks only fourth in importance among the blood changes found. It would seem from this that perhaps too much importance has been placed in the past upon stippling as such, as too little emphasis upon the blood picture as a whole. This blood picture does not give one the impression of stippling above all else, but rather presents the picture of an anemia.
Space does not permit of a detailed discussion of the various abnormal elements in the blood picture presented by these lead workers. Suffice it to say that the red blood cell count though as low as 2, 800,000 in a few instances, was on the whole not very much reduced. The average found was 4,000,000 which is 80 per cent of the 5,000,000 regarded as normal for the adult male. The average hemoglobin found was 79 per cent., giving a color index of very little less than one. This anemia, then, appears to be a very mild secondary anemia. Indeed, one can readily see how in a given case, an examination of the red cell count and the hemoglobin might reveal changes in the two factors which are so slight as to cause no suspicion that more significant blood changes have occurred.
But the significant thing which was found to distinguish lead anemia from the ordinary secondary anemia is this: that accompanying an anemia which from the red cell count and the hemoglobin may appear to be very slight indeed, there may be such serious blood changes as stippling, polychromatophilia, the presence of nucleated red cells in considerable numbers, anisocytosis, Poikilocytosis, and even eosis myelocytes, and turks irritation cells.
These abnormal cells are found in the other secondary anemias, and in pernicious anemia, but only where anemia is severe and in these cases there is a very marked reduction in the red cell count and the hemoglobin, usually in both in lead anemia these cells apparently may accompany so slight a reduction of red cells and hemoglobin as not to be at all suspected as a result of the usual routine examination of the blood. Moreover, these abnormal cells are not necessarily always associated with stippling.
It appears, therefore that an examination of the blood for the red cell count, the hemoglobin and for stippling does not necessarily reveal the other important abnormal blood elements which go to make up the typical lead anemia. A diagnosis, therefore, without a careful examination of the blood for all of the abdominal blood elements is just as unsatisfactory for the diagnosis of lead anemia as it is unsatisfactory to a proper diagnosis of any other other anemias. A diagnosis is never made in the case of other anemias without a through examination of the whole blood picture. The same thoroughness is required in the examination of the blood of a lead worker, if a proper estimation is to be arrived at with reference to whether his exposure to this metal has adversely affected his blood, or not.
It is hoped and believed that the recognition of lead anemia as an entity of which stippling is only one of many factors, should materially assist in increasing the value of the blood findings for the diagnosis of lead poisoning. For example, in the numerous cases which are so troublesome to the compensation courts, where the symptoms complained of are so vague as to bear none of the definite earmarks of lead poisoning, the blood picture should be of material assistance.
If a worker is incapacitated from work because of headache, dizziness or loss of appetite all of which might be due to a thousand and one causes other than exposure to lead the finding of a typical lead anemia, either with or without stippling, should clinch the diagnosis. Undoubtedly there will be cases where even with the entire blood picture at hand the diagnosis will will remain in doubt. But on the whole it is to be expected that the whole blood picture will give considerably more valuable information than would be the mere fact of the presence or absence of stippled cells. Industrial Hygiene Bulletin.