This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
It is commonly held that iodine stimulates the absorbent glands to increased action. This may be an indirect effect consequent upon its breaking down and rendering more susceptible of absorption certain kinds of tissue. It may be connected also with its quickening capillary circulation in the secretory glands.
The salivary glands and the pancreas, and possibly the lachrymal glands and those of mucous membrane and the testes, have their secretion increased by it. Rutherford concluded that the bile was not affected in quantity (British Medical Journal, 1879).
The secretion of milk is usually lessened under the influence of iodides, and may be almost wholly prevented by small doses commenced soon after delivery. If already established, it may be suppressed by the same treatment if the infant be not placed to the breast (Morris: Lancet, ii., 1864). There are, however, some observations to the contrary, e.g., those of Lazansky (Medical Record, 1878), who states that iodine does not affect the secretion; and certainly it may be given to syphilitic nursing mothers without stopping the flow of milk, when this has been established for several months.
Whether iodine can cause atrophy of true glandular structure is an important question which is not yet decided in the affirmative, though Rilliet accepts its truth in the case of the testes and mammae. Moisisovitz states that iodine has this effect, but not the iodides; he refers to eight hundred patients (Canstatt, 1866).
Certainly large quantities have been given without any such occurrence. Rabuteau gave to a woman, in the course of six years, 3 kilogrammes of iodide of potassium, yet the breasts were not at all affected by it; and Velpeau never observed wasting in fifteen thousand cases treated by him (Medico-Chirurgical Review, ii., 1860). On the other hand, one case of wasting of the testes is recorded, but is not convincing (Philadelphia Medical Times, iv., 661). An enlarged and hard gland will grow less under these remedies from absorption of hyperplastic material, and even a healthy gland may grow smaller from absorption of fat or epithelial products; but, so far as I have seen, the breasts, etc., recover their natural appearance on omission of the remedy, which they would not do if the gland-structure were actually destroyed.