Cardiorespiratory, hematological and physical performance responses of anemic subjects to iron treatment.

Twenty-nine adult iron-deficient anemis subjects (13 men and 16 women) with hemoglobin levels of 4.0 to 12.0 g/100 ml blood were divided into either an iron treatment or placebo group. Hematological, cardiorespiratory and performance data were collected before, during, and after treatment and compared with data from a control group of subjects (4 men and 6 women) from the same socioeconomic population. Hemoglobin levels for the iron treatment group improved from 7.7 to 12.4 g for the women and from 7.1 to 14.0 g for the men. Values for the control group were 13.9 g and 14.3 g for the women and men, respectively. The placebo group showed virtually no change over the 80-day period (8.1-8.4 g for women and 7.7-7.4 g for men). Peak exercise heart rates (5 min, 40-cm step test) were significantly reduced after treatment from 155 to 113 for the iron treatment men and 152 to 123 for the women compared with the placebo group which showed no changes. Values for the control group were 119 and 142 for the men and women, respectively. In response to the exercise test, no difference in oxygen consumption was found between the iron treatment and placebo group although 15% more O2 was delivered per pulse in the iron treatment group. Blood lactates were significantly highein the placebo than iron treatment group both at rest, 1.18 versus 0.64 mmole/liter, and 1 min after exercise, 5.30 versus 2.68 mmoles/liter. No changes in handgrip or shoulder adductor strength were observed following treatment. These results clearly support the concept that performance requiring high oxygen delivery is significantly affected by hemoglobin levels.

Serum lipid levels in iron deficiency anemia and effects of various treatments.

Effects of anemia on serum total cholesterol and triglyceride levels were studied in Sri Lanka. In subjects with hemoglobin (Hb) levels of less than 9.0 g/100 ml, there was a significant relationship between Hb and cholesterol levels (r = 0.53). This relationship was not seen in subjects with Hb levels equal to, or greater than, 9.0 g/100 ml. Triglyceride levels were independent of Hb levels. Total cholesterol levels were elevated following an increase in Hb levels by transfusion and iron treatment. It was suggested that the concentration of red blood cells may affect cholesterol synthesis or mobilization from tissue to plasma.

Characteristics of blood gas in response to iron treatment and exercise in iron-deficient and anemic subjects.

The effects of iron deficiency anemia and iron treatment on blood gas and acid-base balance at rest and during exercise were studied. Eight Sri Lankan males and 13 females were randomly divided into an iron treatment or placebo group. Their initial hemoglobin (Hb) levels were 6.2 +/- 0.5 and 5.5 +/- 0.7 g/100 ml (mean +/- SEM) with serum iron levels of 41 +/- 8 and 30 +/- 6 micrograms/100 ml, respectively. Hemoglobin concentration was increased significantly within 7 days after iron treatment to 7.2 +/- 0.4 g/100 ml. Resting lactate was higher than normal, while base excess, buffer base, and actual bicarbonate were lower, maintaining a normal pH. Heart rates during exercise at a given work load and lactate production following exercise decreased after the elevation of Hb. Venous blood PCO2 rose as Hb concentration increased, preceding a significant increase in resting O2 content, 16 days after iron treatment. With anemia, O2 delivery is potentially maintained by a shift of the O2-dissociation curve to the right due, in part, to 2,3-diphosphoglycerate. There was no significant change in PO2 or Hb-O2% saturation following exercise or iron treatment. These data suggest that severe iron deficiency anemia results in lactate accumulation in blood even at rest but pH is maintained within normal limits. It was also suggested that severe anemia may impair CO2 transport capacity of blood which could limit continuation of muscle metabolism.

Elevation of hemoglobin and work tolerance in iron-deficient subjects.

Selected parameters related to work tolerance were measured in 31 adult subjects with hemoglobin (Hb) concentration from 2.5 to 14.0 g/100 ml. Work tolerance was closely related to Hb concentration (r = 0.74) regardless of the adequacy of storage iron level. One male and six females with a mean Hb of 3.5 g/ml (27-55 years old) were studied before and 24h after transfusing 570ml of whole blood. The mean maximal work load tolerated increased 83% within 24h after transfusion in these seven subjects. Post-exercise venous blood lactate was markedly lower after transfusion. Work tolerance of these subjects within 24h after transfusion was the same as in other subjects who had had the equivalent Hb level as the post-transfusion subjects presumably for at least several weeks. These data suggest that the decrement in work performance capacity in iron-deficient and anemic subjects is, in a large part, a reflection of the level of anemia rather than other non-Hb related biochemical changes that could accompany prolonged iron deficiency anemia.

Work capacity after iron treatment as a function of hemoglobin and iron deficiency.

The relative importance of hemoglobin (Hb) and non-Hb iron for physical work capacity was studied in 45 adult male and female subjects, with a range of Hb and serum iron levels. Maximal work capacity, heart rate, venous blood lactate and serum protein were measured before and after 1 week of treatment with Imferon, i.v. Even though some non-Hb related effects on parameters indicative of maximal work capacity were found, the main factor was Hb related. Subjects with low Hb-high serum iron worked longer than ones with low Hb-low iron. When work performed was similar, the marginal Hb-low iron group had a higher blood lactate concentration than the high Hb-high iron and marginal Hb-high iron groups. The coefficient of correlation between serum iron and post-exercise lactate levels was -0.41 (p less than 0.05). Even though neither of these groups showed a Hb response within 1 week of iron treatment, the initial low serum iron groups had significantly lower heart rates at a given work load relative to subjects with high iron but with a similar Hb level. This occurred both at rest and during light to heavy exercise. These results suggest that a rather rapid benefit of iron treatment is gained in iron-deficient subjects with severe and moderate anemia which cannot be accounted for by Hb changes. Although the primary factor which affects the physical work capacity of iron-deficient anemic subjects seems to be the Hb level, there also seems to be a significant non-Hb related effect of iron treatment as well.

"Ischemic" heart disease in fire fighters with normal coronary arteries.

Near maximal stress testing conducted on a group (N = 90) of randomly selected Los Angeles City fire fighters (age 40-59 yrs.) revealed that 10% had ischemic ECG changes. These ischemic ECG responses were confirmed during a second test conducted two to four weeks after the initial test. Coronary heart disease (CHD) risk factor analysis revealed that in general the men were not at high risk for CHD. Six of the nine men elected to undergo cardiac catheterization and angiography. One patient had severe triple vessel disease and subsequently underwent aorto-coronary bypass surgery. Another had 50% obstruction in the circumflex branch of the left coronary while the other four men had no visable signs of coronary obstruction. The men with "normal" coronaries, however, did show signs of abnormal cardiac function during atrial pacing. One man had cardiac enlargement, hypokinesis, ischemic ECG and abnormal lactate metabolism. Another had abnormal lactate metabolism and ischemic ECG. A third man had moderate cardiac enlargement with anterior wall hypokinesis. The fourth had ischemic ECG changes with angina but otherwise normal cardiac function. All four of these men had pressures which were within normal limits. These data show that some fire fighters have "ischemic" heart disease with patent coronary arteries. This disease may be due to job related factors (i.e. carbon monoxide and other noxious fumes, catecholamines, etc.) which reduce myocardial oxygen supply or greatly increase myocardial oxygen demands.

Iron-deficiency anaemia and its effect on worker productivity and activity patterns.

The effects of iron-deficiency anaemia on workers productivity were studied in a tea plantation in Sri Lanka. The quantity of tea picked per day was studied before and after iron supplementation or placebo treatment. After one month's treatment significantly more tea was picked when the haemoglobin (Hb) concentration was increased by iron supplementation than when it was not. The degree of improvement was greater in more-anaemic subjects (those with concentrations of 6.0-9.0 g Hb/dl). The level of physical activity of anaemic subjects in their everyday environment was also recorded for four or 24 hours continuously both before and after treatment. After three weeks these levels was significantly greater in the iron-treated than matched placebo-treated subjects. The economic implications of increased work productively with iron treatment are evident, particularly in developing countries. These results also provide strong evidence for the clinical impression that people with iron-deficiency anaemia suffer from tiredness and weakness.

Near-maximal ECG stress testing and coronary artery disease risk factor analysis in Los Angeles City fire fighters.

Near-maximal ECG stress testing and coronary artery disease risk factor analysis including blood pressure, serum cholesterol and smoking habits were conducted on a randomly selected group (N=90) of Los Angeles City Fire Fighters ranging in age from 40 to 59 yrs. The data obtained from the fire fighters were compared to data previously reported for a group of Los Angeles insurance underwriters of the same age range. Only 12% of the fire fighters had cholesterol values greater than 260 mg% while 18% of the insurance executives fell into this category. Only 2% of the fire fighters had blood pressure values greater than 160/90 mm Hg while 25% of the insurance executives were hypertensive. Thirty-two percent of the fire fighters were smokers at the time of testing as compared to 26% for the insurance executives. Only one fire fighter had all three risk factors elevated and only five had two risk factors elevated. Forty-seven of the fire fighters had no risk factors elevated. Ten percent of the fire fighters had ischemic stress tests as compared to 8% for the insurance executives. Of the nine fire fighters with ischemic stress tests one was hypertensive, one had elevated serum triglycerides, and three were smokers at the time of testing. Since the fire fighters are a medically-selected population with low risk factors for CHD, the observed incidence of ischemic stress tests is surprising and suggests that ischemic heart disease may be job associated.

Work capacity, heart rate and blood lactate responses to iron treatment.

Changes in haemoglobin (Hb), work performance, heart rate and postexercise blood lactate were studied in iron deficient, anaemic subjects for 16 d following total dosage infusion of iron dextran, i.v. (30-50 ml). Six adult men and 14 women were subjects with initial Hb levels of 6.6 +/- 0.6 g/dl (mean +/- SEM) for the iron treatment group (n=10) and 8.0 +/- 0.7 for the placebo group (saline infusion, n=10). Serum levels were 0.51 +/- 0.15 and 0.67 +/- 0.12 mg/l for the two groups, respectively. Haemoglobin and maximal work time increased significantly within 4 d after iron treatment and continued to increase up to 16 d. No changes were found in the placebo subjects. Heart rates at a given exercise intensity were lower in the iron treatment group than in control subjects who had the same Hb levels but had not been treated with iron. Post-exercise venous blood lactate was similar on succeeding days after iron treatment even though the subjects reached higher work loads. These results demonstrate the treatment of iron deficient, anaemic subjects with iron dextran results in improved work capacity within 4 d and a lower heart rate at a given work load after treatment which cannot be accounted for totally by the elevation of Hb concentration.