McCarrison has stressed the importance of endocrine disturbances in dietetic deficiencies and notes atrophy of all the glands of internal secretion in such conditions with the exception of the adrenal which tends to hypertrophy. There is possibly some hypertrophy of the pituitary in males. The oedema which accompanies most of the food deficiency diseases he associates with the adrenal enlargement and hyperactivity of function, although oedema does not invariably result from such hypertrophy. In pellagra there is a low blood pressure, possibly due to adrenal hypofunction. Goitre is found in many parts of the tropical world and Castellani states that this disease is met with frequently in Ceylon and various regions of Africa. Disturbances of the internal secretion of the pancreas, resulting in diabetes, are common in parts of Asia.
Determination of Basal Metabolism.—In the study of cases where abnormal thyroid functioning is suspected the most accurate method of such determination is by estimating the percentage of the patient’s metabolism as above or below the normal average.
Basal metabolism is that caloric value which an individual produces while resting in bed and prior to taking breakfast—in other words when the effects of food and exercise on caloric output are least operative. Basal metabolism is expressed in terms of calories per hour per square meter of body surface. It varies with different ages. It is proportionate to body surface which is calculated from the height and weight of the individual. Normally this metabolism should not vary more than 15% above or below accepted normal figures. The use of the respiration calorimeter is the most accurate method for determination of heat production but it has now been found that the oxygen consumption during short periods gives data for calculation of such heat production (indirect calorimetry). In the Benedict portable respiration apparatus the patient breathes into and out of a confined volume of air circulating through a series of purifiers which remove the carbon dioxide. A determination of the volume of oxygen consumed is made from the decrease in the total air volume. The heat production resulting from the absorption of one litre of oxygen is relatively constant whether used to burn fat or carbohydrate and gives an accurate index of total heat production. The Benedict apparatus can also be employed for determining carbon dioxide excretion and thereby giving data for the respiratory quotient. The determination of the heat produced in the excretion of carbon dioxide is less accurate although easier of determination. In marked cases of hyperthyroidism the basal metabolism ranges 75% above the normal figures, between 50 and 75% for severe cases and less than 50% for mild cases. In hypothyroidism the figures are usually 20 to 40% below the normal averages. The average respiratory quotient is taken as O.82 and the calorific value of oxygen at this respiratory quotient is 4.825 per litre. We multiply the litres of oxygen by 4.825 to compute the heat output. It must be remembered that patients with high fever give 30 to 40% heat production over normal figures. Severe cardiac and renal conditions as well as leukaemias also give high values. The average calorie output per square meter of body surface per hour based on the Du Bois “height-weight” formula, is 39.7 for man and 36.9 for women between the ages of 20 and 40, being greater in youth and less beyond forty.
Focal Infections.—In recent years our attention has been directed to the importance of certain localized bacterial foci which may extend through blood or lymph channels and give rise to various systemic or localized diseases. Most important of these diseases are various types of arthritis together with endocarditis, myocarditis and pericarditis. Next in importance are renal infections, chiefly of the glomerulonephritis type.
Cholecystitis, appendicitis, pancreatitis and various skin lesions may also have origin in a focal infection. The primary foci may be localized in any part of the body but those seated in the tonsilar, peridental membrane, nasal and accessory sinus tissues are the most common and important. Focal infections of the genito-urinary tract may also give rise to generalized conditions as is also true of such foci in the alimentary tract. In the tonsils we should particularly examine the material of crypts for various streptococci and likewise the bacterial flora of tooth abscesses or pyorrhoea alveolaris.
Table Showing Number of Times Each Focus Was Considered a Probable Source of Infection in a Series Studied by Billings and Associates
| No. | No. | ||
| Tonsil | 336 | Prostate and genito-urinary tract | 24 |
| Teeth | 136 | Gallbladder | 3 |
| Sinus | 12 | Enterocolitis | 2 |
| Bronchi | 5 | Appendix | 1 |
| Uterus and tubes | 12 | Middle ear | 1 |
CHAPTER XLIV
ONSET AND THE TEMPERATURE CHART IN THE DIAGNOSIS OF TROPICAL DISEASES
While a knowledge of the variations in type and course of the body temperature in the various tropical diseases is of great value in diagnosis, yet such information is liable to lead one astray, unless such data are controlled by a careful consideration of the other and, in my opinion, more important factors of physical diagnosis and laboratory examinations.