Idiopathic edema. I. The occurrence of hypoalbuminemia and abnormal albumin metabolism in women with unexplained edema

Clinical Characteristics of Overhydration in Patients with Idiopathic Edema

BACKGROUND

Idiopathic edema (IE) is a common clinical syndrome. Designing treatment plans for IE is problematic because of the difficulty in assessing volume status. We aimed to evaluate volume status, measured by bioimpedance spectroscopy (BIS), and investigated clinical parameters associated with volume overload (VO) in patients with IE.

METHODS

Patients with IE were defined as those with symptomatic edema and without abnormal renal function or any other apparent cause of edema. A total of 124 patients were included. Overhydration (OH) and extracellular water (ECW) were calculated using BIS. Relative hydration status (x0394;HS) was defined as OH/ECW. Patients were classified into 2 groups: overhydrated group (OG; x0394;HS ≥7%) and non-OG (NOG; x0394;HS <7). Simple and multiple logistic regression analyses were used to assess the influence of several variables on the incidence of VO.

RESULTS

Of 124 patients, 37 (29.8%) were in the OG. The proportion of men in the OG was higher than that in the NOG (p = 0.020). Patients in the OG showed more frequent pretibial pitting edema (PTPE, p < 0.001) and had lower hemoglobin (p = 0.008) and serum albumin levels (p < 0.001). The multivariate analysis showed that the presence of PTPE (OR 10.62, 95% CI 1.98-57.1), low serum albumin level (OR 0.01, 95% CI 0.00-0.25) and lower fat tissue index (OR 0.78, 95% CI 0.63-0.97) were independent risk factors for the presence of VO.

CONCLUSIONS

BIS helps to identify volume status and body composition in patients with IE.

Albumin metabolism and gastrointestinal loss of protein in chronic renal failure

The catabolism of albumin labelled with 125I has been studied in 10 patients with advanced renal failure and in 5 with nephrotic syndrome. In 10 patients the gastrointestinal protein loss was studied simultaneously by determing the faecal excretion during 7 days of 51Cr after i.v. administration of 51Cr-labelled chromic chloride. The results were related to a control group in which 12 subjects were studied with respect to albumin catabolism and 17 with respect to the gastrointestinal protein losses. The results showed that: 1) In the two patient groups the means for serum albumin concnetration and the intravascular albumin pool, expressed as g or g/kg b.wt., were significantly decreased compared with those of the control group. 2) The two patient groups had an increased extravascular albumin pool as well as an elevated ration between extra- and intravascular pools. 3) The mean albumin catabolic rate was not increased in the renal insufficiency group, expressed as a percentage of the intravascular pool/24 h or as g/24 h. In the patients with nephrotic syndrome, however, it was significantly increased. 4) The renal insufficiency group had a mean cumulative 51Cr excretion during 7 days of 1.6+/- 0.80% of the given dose, the control group 0.63+/- 0.30%. This difference is highly significant. The patients with nephrotic syndrome did not differ from the control group.

The 3H-leucine tracer: its use in kinetic studies of plasma lipoproteins

3H-leucine administered as a bolus has been widely used as a tracer in kinetic investigations of protein synthesis and secretion. After intravenous injection, plasma specific radioactivity decays over several orders of magnitude during the first half-day, followed by a slow decay lasting a number of weeks that results from recycling of the leucine tracer as proteins are degraded and 3H-leucine reenters the plasma pool. In studies in which kinetic data are analyzed by mathematical compartmental modeling, plasma leucine activity is generally used as a forcing function to drive the input of 3H-leucine into the protein synthesis pathway. 3H-leucine is an excellent tracer during the initial hours of rapidly decreasing plasma activity; thereafter, reincorporation of recycled tracer into new protein synthesis obscures the tracer data from proteins with slower turnover rates. Thus, for proteins such as plasma albumin and apolipoprotein (apo) A-I, this tracer is unsatisfactory for measuring fractional catabolic (FCR) and turnover rates. By contrast, the kinetics of plasma very-low-density lipoprotein (VLDL)-apoB, a protein with a residence time of approximately 5 hours, are readily measured, since kinetic parameters of this protein can be determined by the time plasma leucine recycling becomes established. However, measurement of VLDL-apoB specific radioactivity extending up to 2 weeks provides further data on the kinetic tail of VLDL-apoB. Were plasma leucine a direct precursor for the leucine in VLDL-apoB, the kinetics of the plasma tracer should determine the kinetics of the protein. However, this is not the case, and the deviations from linearity are interpreted in terms of (1) the dilution of plasma leucine in the liver by unlabeled dietary leucine; (2) the recycling of hepatocellular leucine from proteins within the liver, where recycled cellular leucine does not equilibrate with plasma leucine; and (3) a "hump" in the kinetic data of VLDL-apoB, which we interpret to reflect recycling or retention of a portion of the apoB protein within the hepatocyte, with its subsequent secretion. Because hepatocellular tRNA is the immediate precursor for synthesis of these secretory proteins, its kinetics should be used as the forcing function to drive the modeling of this system. The VLDL-apoB tail contains the information needed to modify the plasma leucine data, to provide an appropriate forcing function when using 3H-leucine as a tracer of apolipoprotein metabolism. This correction is essential when using 3H-leucine as a tracer for measuring low-density lipoprotein (LDL)-apoB kinetics. The 3H-leucine tracer also highlights the importance of recognizing the difference between plasma and system residence times, the latter including the time the tracer resides within exchanging extravascular pools. The inability to determine these fractional exchange coefficients for apoA-I and albumin explains the failure of this tracer in kinetic studies of these proteins. For apoB-containing lipoproteins, plasma residence times are generally determined, and these measurements can be made satisfactorily with 3H-leucine.

Opioid peptides, adrenocorticotrophic hormone, and idiopathic (orthostatic) edema

The effect of dextroamphetamine sulfate (Dexedrine) on plasma opioid peptides, hormones, and other metabolites was studied in eight female subjects with idiopathic (orthostatic) edema and five healthy females. All subjects were given 20 mg of dextroamphetamine sulfate, a drug widely used in the treatment of this disorder, and blood samples were collected before and 30, 60, and 90 minutes after treatment. Patients with idiopathic (orthostatic) edema had significantly lower plasma sodium levels but higher blood urea nitrogen, aldosterone, and renin levels. D-amphetamine decreased aldosterone and renin levels in both groups. Plasma adrenocorticotropin levels were lower whereas met-enkephalin levels were higher in idiopathic (orthostatic) edema subjects compared to control subjects. D-amphetamine had no significant effect on plasma beta-endorphin, adrenocorticotrophic hormone, or enkephalins. Our data indicate that opioid peptides, especially enkephalins, and adrenocorticotrophic hormone may be involved in the pathogenesis of idiopathic (orthostatic) edema syndrome, but they seem uninvolved in the aldosterone- and renin-lowering action of amphetamine. It is possible that amphetamine is acting further down the chain, either directly on the adrenal and kidney or the microvasculature, rather than at hypothalamus-pituitary axis.

Osmoregulation of vasopressin secretion and thirst in cyclical oedema

Osmoregulation of vasopressin release and thirst was studied in the mid-follicular and mid-luteal phases of the menstrual cycle of five patients with cyclical oedema defined by peripheral oedema and weight gain (greater than 3.0 kg) manifest in two consecutive luteal phases. Results are compared to those already obtained in eight healthy women. In the patients, basal plasma osmolality in the mid-luteal phase was significantly lower than in the mid-follicular periods (patients, 283 +/- 1, 287 +/- 1 mOsmol/kg, respectively, mean +/- SEM, P less than 0.05; controls, 282 +/- 1, 286 +/- 1 mOsmol/kg, respectively, P less than 0.05). Plasma osmolality (pOsm) and plasma arginine vasopressin (pAVP) were measured during hypertonic (850 mmol/l) saline infusion in both phases of the cycle; linear regression analyses of these data gave the following mean regression equations, (i) mid-follicular, pAVP = 0.55 (pOsm - 285), r = 0.94 and (ii) mid-luteal, pAVP = 0.42 (pOsm - 281), r = 0.93. The abscissal intercept was significantly different (P less than 0.025). Osmotic threshold for severe thirst onset was lower in the mid-luteal phase compared to the mid-follicular value (296 +/- 1, 299 +/- 1 mOsmol/kg, respectively, P less than 0.01). Basal data and results of thirst onset and theoretical threshold for vasopressin release in response to osmotic stimulation obtained in the patients were similar to healthy control women. We conclude that osmoregulation in cyclical oedema is normal.

[Unexplained edema in females--diuretic-induced or idiopathic?]

Both women with diuretic induced edema and with idiopathic edema present a typical history leading to the diagnosis in most cases. These women are almost exclusively in the reproductive age and they tend to have some other characteristics in common additionally. There is controversy whether idiopathic edema exists as a syndrome with multifactorial pathogenesis or if fluid retention in these women is due to diuretic abuse. In either case the use of diuretics is not indicated as they can increase and perpetuate the edema and moreover may bring about impairment of renal function. Abstinence of diuretic intake is the only way out of the vicious circle of fluid retention induced by intermittent diuretic intake resulting in intermittent edema and prostrained use of diuretics. Therapy of idiopathic edema is difficult; it includes physical therapy, psychotherapy and pharmacotherapy with aldosterone antagonists or ACE-inhibitors in some severe cases.

Altered dopaminergic modulation of sympathetic nervous system activity in idiopathic edema

Hormonal and mean arterial pressure responses to posture and isometric handgrip exercise were examined in 6 women with idiopathic edema and 10 age- and weight-matched normal women before and after 5-7 days of administration of the dopamine agonist, bromocriptine (2.5 mg three times a day). Edema patients demonstrated greater orthostatic weight gain, greater upright epinephrine values, and greater supine and upright norepinephrine values than did the control group. However, supine and upright plasma dopamine levels were similar in the two groups. In edema patients there was a greater supine and posture related norepinephrine and epinephrine to dopamine ratio than in normal controls. These abnormalities were not corrected by treatment with bromocriptine. Supine and upright plasma norepinephrine and epinephrine levels were decreased following bromocriptine treatment in normal subjects but not in edema patients. These data are consistent with the concept that there is decreased dopaminergic regulation of sympathetic nervous activity in patients with idiopathic edema.

Idiopathic edema as a cause of nonarticular rheumatism

Six women, aged 24 to 53, presented with symptoms of diffuse aching, morning stiffness, and fatigue, but demonstrated no objective abnormalities on joint examination or in laboratory studies. Each was found to have idiopathic edema, a disorder of fluid retention probably related to an abnormality of capillary permeability in which transudation of fluid into the subcutaneous tissues of dependent parts may result in swelling and discomfort. The rheumatic symptoms improved when therapeutic measures were directed against the accumulation of edema fluid. This syndrome may account for a minority of cases of nonarticular rheumatism in women.

Hypovolaemic shock with oedema due to increased capillary permeability

A case of severe hypovolaemic shock related to idiopathic oedema was observed in a 37 year old woman. Large plasma volume expansion (nearly 12 1 over 9 hours) did not change the clinical status. Haemodynamic studies showed low cardiac index (1.1 1/min/m2), decreased left ventricular stroke work index (6.7 gm/m2), and high systemic arterial resistance (52 mmHg/1/min/m2). Dopamine infusion improved the haemodynamic condition which returned to normal 30 hours after the beginning of shock. After recovery, capillary permeability measured by a modification of Landis' method was markedly increased. A study of albumin metabolism showed a normal intravascular pool and a rapid exchange compartment with a twofold increase in slow exchange compartment. Hormonal levels and complement fractions were within normal limits. Serum protein immuno-electrophoresis showed an abnormal IgG. These results clearly demonstrate that hypovolaemia is related to increased capillary permeability and leakage of albumin out of the vascular space. When large infusions fail, inotropic agents, especially Dopamine, should be used in such cases.

[Idiopathic edema, capillaropathy, pericardial and pleural effusions with high protein content (author's transl)]

Clinical and electron microscopic studies of two female patients are reported who, in addition to the symptoms and signs of idiopathic edema, had pericardial (and pleural) effusions. In one patient pericardiectomy had to be performed, in the other patient pharmacotherapy with spironolactone was effective. In these patients the protein-concentrations of edema fluid (25 and 12 g/l) and pericardial fluid (55-61 and 48 g/l) were relatively high; the distribution space of labelled protein was increased; blood volumes were low-normal or decreased. Electronmicroscopy of the microvasculature showed identical alterations in both cases. In the cutaneous vessels the endothelium developed numerous abnormal cytoplasmic processes and intercellular "gaps". In the capillaries of skeletal muscle our findings indicate an increase in vesicular transport. We suggest the electron microscopic alterations to be the morphologic correlate for the increased transport and extravascular accumulation of protein. Changes as they are described here in humans with idiopathic edema have been documented before in animals with experimental edema.

Sodium metabolism

This brief review attempts to summarize important basic concepts of sodium metabolism including sodium ion distribution, sodium balance and the renal regulation of sodium excretion. Finally, an attempt has been made to relate these basic concepts to the mechanisms and management of common clinical situations of abnormal salt balance.

[Catamnestic and endocrinological investigations in women with idiopathic edema (author's transl)]

The clinical picture and the course of idiopathic edema is described after evaluating catamnestic questionnaires on 39 patients. It appears that the syndrome often occurs in other female family members, especially in mothers of propositi and that two thirds of patients have also suffered from symptoms of allergy. In contrast to observations of other groups, diabetes mellitus and slight hypoalbuminemia were found only in a few patients. Secondary hyperaldosteronism was almost exclusively observed in patients who had been taking diuretics during the last few days before the measurements were done. The plasma concentrations of 6 other adrenal steroidal hormones were measured in 33 patients. Only in few of them, mostly patients who had taken diuretics, increased level of 11-deoxycorticosterone, 18-OH-11-deoxycorticosterone and corticosterone were observed. Idiopathic edema does not seem to be a disease entity, but some prediposing factor related to the female reproductive system is likely to exist. Results of systematic psychosomatic studies in our patients will be reported later on.

[The regulation of serum albumin in physiological and pathological conditions (author's transl)]

12 g of albumin are synthesized daily by the bound polyribosomes of all human liver cells together, corresponding to 10% of the intravascular albumin mass. The cell is producing a precursor albumin. During secretion albumin is liberated by splitting of a small peptide. Only 40% of the total body albumin is located intravascularly. 12g of albumin are degraded or excreted daily, 30% of it by the liver, the kidneys and the gastrointestinal tract. The main site of albumin catabolism is unknown. Albumin with a half-life of about 20 days is degraded at a constant fractional catabolic rate. The absolute rate of degradation varies depending on the plasma content. This mechanism allows an effective regulation of the serum albumin level. The fractional catabolic rate, however, is not completely fixed. It is slowly reduced if the serum albumin content is markedly reduced as in protein deficiency, the blind loop syndrome, cirrhosis, nephrosis, and diseases of the gastrointestinal tract. Infusion of albumin increases the fractional catabolic rate slowly. This must be taken in consideration substitution albumin in chronic diseases. The shift from the extravascular to the intravascular compartment is a short-term regulatory mechanism. The regulation of synthesis and degradation are independent from each other. The molecular mechanism of regulation of synthesis and degradation are unknown, partially due to inadequate methods.