Macro- and micronutrient losses and nutritional status resulting from 44 days of total fasting in a non-obese man

OBJECTIVE

We wanted to establish and understand how the fractional losses of fat, fat-free tissues, and selected nutrients compare with that of body mass during a 44-d voluntary starvation (water only) and measurements of nutrient status.

METHODS

We used anthropometry, sequential measurements of urinary substances during the fast, and blood analytes at the end of the fast.

RESULTS

At the start of the fast, body weight was 96.0 kg (20% fat) and body mass index was 28.36 kg/m(2). The changes in body mass and arm anthropometry and in the pattern of urinary excretion of creatinine, ammonia, sodium, and ketone bodies during the study were consistent with starvation. At the end of the fast, body mass had decreased by 25.5%, of which a quarter to a third was due to loss of fat and the remainder to fat-free mass, predominantly muscle. There was an estimated loss of 20% of total body protein, 20-25% of fat-free mass, and a greater fractional loss of fat. Total energy expenditure was estimated to be 1638-2155 kcal/d of which 13.0-17.1% was from protein oxidation. Differential losses of minerals in urine ranged from 1.2% of estimated initial body content for manganese to 17.3% for selenium and 40.5% for zinc. At the end of the study, plasma concentrations of zinc and vitamin B12 were increased, those of copper, selenium, and manganese were normal, and there was biochemical evidence of deficiency in thiamine, riboflavin, and vitamin K (prothrombin time).

CONCLUSION

The data confirm and extend the available information on prolonged fasting in lean individuals and have relevance to the understanding of the physiologic responses to starvation and the associated homeostatic mechanisms.

Identification of functions of peroxisome proliferator-activated receptor alpha in proximal tubules

Peroxisome proliferator-activated receptor alpha(PPARalpha) is a member of the steroid/nuclear receptor superfamily that is intensively expressed in the kidney, but its physiologic function is unknown. In this study, PPARalpha-null mice were used to help clarify the function. Starved PPARalpha-null mice were found to secrete significantly more quantities of urine albumin than starved wild-type mice. Furthermore, the appearance of giant lysosomes, marked accumulation of albumin, and an impaired ability concerning albumin digestion were found only in proximal tubules of the starved PPARalpha-null mice. These abnormalities were probably derived from ATP insufficiency as a result of the starvation-induced decline of carbohydrate metabolism and a lack of PPARalpha-dependent fatty acid metabolism. It is interesting that these abnormalities disappeared when glucose was administered. Taken together, these findings demonstrate important functions of PPARalpha in the proximal tubules, the dynamic regulation of the protein-degradation system through maintenance of ATP homeostasis, and emphasize the importance of the fatty acid metabolism in renal physiology.

Plasma N tau-methylhistidine concentration is a sensitive index of myofibrillar protein degradation during starvation in rats

Urinary excretion of N tau-methylhistidine (MeHis) in rats was linearly elevated by starvation for 2 days. Plasma concentration of MeHis on day 1 and day 2 of starvation were increased 2.4- and 2.6-fold, respectively. The amount of released MeHis from the isolated muscles into medium during a 2-h incubation period was increased with starvation corresponded to the plasma MeHis concentration. The results of this study suggest that plasma MeHis is a sensitive index of myofibrillar protein degradation.

Effects of starvation and of selenium deficiency on the urinary excretion of electrolytes, ketone bodies, creatinine, urea and uric acid

The aim of this study was to investigate whether urinary excretion of other compounds than ketone bodies are also increased in starved, selenium (Se)-deficient rats. Two groups of male rats were fed an Se-deficient diet with 0.009 mg Se/kg, ("Se-deficient" and "Se-repleted") and one group was fed the same diet with 0.23 mg Se/kg as control for eleven weeks. The urinary excretion of ketone bodies was highly enhanced in Se deficiency, with a 7-fold increase in 3-hydroxybutyrate and an 18-fold increase in acetoacetate. Despite this, the plasma concentration of ketone bodies and the glomerular filtration rate were unaffected in the Se-deficient rats. Starvation resulted in a significant decrease in the urinary content of potassium, magnesium and calcium, in both dietary groups of rats and of urea in the Se-adequate group. No Se-dependent difference was noted for the urinary excretion of these compounds or of sodium, phosphate, creatinine and uric acid in any of the groups. This was unexpected in view of certain previous results and indicates that disturbances in the renal handling of compounds are progressive in Se deficiency, with increased excretion of ketone bodies being an early event while more severe deficiency is required to impair the renal handling of electrolytes and other compounds studied.

Central nervous system demyelinating diseases and increased release of cholesterol into the urinary system of rats

The question of what happens to cholesterol in the adult central nervous system during its slow turnover has been addressed using rats with brain and spinal cord labeled with [4-14C]cholesterol upon intracerebral injection of labeled cholesterol into rats at 10-12 days of age. At six months after injection, 14C was found only in the brain and spinal cord and was slowly released via the rat's urine. When labeled rats were given demyelinating agents (triethyl tin chloride, hexachlorophene, sodium cyanide) and when experimental allergic encephalomyelitis was induced, a measurable increase in urinary 14C label above control levels was found. It was concluded that there is a direct relationship between the experimental demyelination induced and the increased release of cholesterol metabolites into urine. The study suggests that a clinical method could be developed to determine the rate of central nervous system demyelination by measuring the amount of urinary cholesterol metabolites.

Substrate uptake and utilization by the kidney of fed and starved rats in vivo

In order to obtain information (1) on the quantitative contribution of various circulating substrates to renal metabolism and (2) on the relative importance of net luminal and basolateral transport for substrate uptake, we have precisely quantified the renal blood flow, the urinary flow, and the rates of substrate handling by the kidney of anesthetized fed and 72-hour-starved rats. For this, the concentration of twelve metabolites were simultaneously measured in arterial and venous whole blood and plasma as well as in urine of each rat thanks to the use of microassays based on enzymatic cycling. In fed rats, the main potential energy sources were glucose and lactate followed by fatty acids, ketone bodies, citrate and glycerol. Starvation caused a large increase in renal uptake and metabolism of fatty acids, ketone bodies, glutamine and glycerol, and a large inhibition of lactate utilization. The net peritubular uptake of acetoacetate, citrate, glycerol and free fatty acids demonstrated in both nutritional states was increased by starvation only for glycerol and free fatty acids; net peritubular efflux of both beta-hydroxybutyrate and ammonium ions was stimulated whereas that of glutamine was converted into net peritubular uptake by starvation.

Increase of urinary ketone body excretion in selenium-deficient rats is a ketone-specific change

The effects of selenium (Se) deficiency on urinary ketone body excretion in starved rats were examined. Rats were fed a basal diet which was Se-deficient (Se content: 0.011 micrograms/g) or a Se-adequate diet (the basal diet supplemented with 0.1 micrograms Se/g as sodium selenite). On the 11th and 22nd week of the feeding period, Se-deficient status in rats fed the basal diet was verified by the observation that the Se content and glutathione peroxidase activity in their plasma, erythrocytes, and livers were markedly lowered. On the 4th, 6th, 11th, 15th, and 22nd week, the rats were starved for 48 h and the urinary excretion of ketone bodies (acetoacetate (AcAc) and 3-hydroxybutyrate (3-OHBA)), urea, and creatinine were examined. The urinary excretion of AcAc and 3-OHBA during the second 24 h of the 48-h starvation period were markedly higher in the Se-deficient rats than in the Se-adequate rats for all weeks examined, while the urine volume and the excretion of urea and creatinine were similar in the Se-deficient and Se-adequate rats, irrespective of the feeding period and the number of hours of starvation. On the 22nd week, the plasma ketone body levels were also determined and significantly higher plasma 3-OHBA levels were observed in the Se-deficient rats than in the Se-adequate rats 72 h after starvation began. These results indicate that Se deficiency causes an increase of urinary ketone body excretion in starved rats and that the increase is ketone-specific with no changes in major urinary profiles.

Lipid mobilising factors specifically associated with cancer cachexia

Both urine and plasma from mice and humans with cancer cachexia have been shown to contain higher levels of lipid mobilising activity than normal controls, even after acute starvation. There was no significant increase in the urinary lipid mobilising activity of either mice or humans after acute starvation, suggesting that the material in the cachectic situation was probably not due to an elevation of hormones normally associated with the catabolic state in starvation. Further characterisation of the lipid mobilising activity in the urine of cachectic mice using Sephadex G50 exclusion chromatography showed four distinct peaks of activity of apparent molecular weights of greater than 20, 3, 1.5 and less than 0.7 kDa. No comparable peaks of activity were found in the urine of a non tumour-bearing mouse. The high molecular weight activity was probably formed by aggregation of low molecular weight material, since treatment with 0.5 M NaCl caused dissociation to material with a broad spectrum of molecular weights between 3 and 0.7 kDa. Lipolytic species of similar molecular weights were also found in the urine of cachectic cancer patients, but not in normal urine even after 24 h starvation. The lipid mobilising species may be responsible for catabolism of host adipose tissue in the cachectic state.

Urinary cortisol and urea nitrogen responses in irreversibly undernourished mule deer fawns

We examined the concentration of urinary cortisol and urea nitrogen of five hand-reared mule deer (Odocoileus hemionus) fawns that failed to recover from winter starvation, and compared them to levels found in fawns that recovered. The fawns wintered in fenced pastures stocked with wild deer, and were put back on supplemental feed after losing 15% of their body mass. The five fawns that died began receiving supplemental feed up to 3 wk before death. All continued to lose weight, and were consequently removed from the pasture and fed ad libitum 4 to 10 days before death. In the animals that died, cortisol levels continued to increase regardless of food availability, and were correlated with those of urea nitrogen. Postmortem cortisol and urea nitrogen measurements were significantly greater than concentrations found in the weeks preceding death. We hypothesize that uncontrolled protein catabolism is promoted by high levels of cortisol. These cortisol levels may reach a point at which irreversible multiple-system organ failure occurs, leading to the animal's death.

Role of the liver in carnitine metabolism: the mechanism of development of carnitine-deficient status in guinea-pigs

It was shown that carnitine deficiency and an impairment of the conversion of butyrobetaine into carnitine develops not only in ascorbic acid-deficient guinea-pigs but also in partially starved animals. We propose that the same mechanism, an absolute or relative ascorbic acid deficiency, is operating in both nutritional states. An increased urinary excretion greatly contributes to the development of carnitine deficiency in guinea-pigs, both in ascorbic acid deficiency and starvation. With respect to the greatly increased excretion, guinea-pig carnitine deficiency resembles the human disorder and may serve as model for it.

[Hormonal and metabolic reactions in the human body during prolonged starvation]

This paper discusses hormonal and metabolic reactions of healthy volunteers exposed to 14-day starvation. This exposure led to many-fold increase of plasma and urinary epinephrine (E); drastic increase of ACTH and beta-endorphin (BE), morning and integrated concentrations of cortisol and STH, aldosterone, T3, glucagon, cAMP, cGMP, cAMP-cGMP, acetyl choline (AC), free fatty acids (FFA), lactate, metanephrine (MN) excretion; decrease of plasma norepinephrine (NE) and unchanged NE excretion; decrease of plasma concentrations of TTH, T4, T3, prolactin (PL), insulin (morning and integrated concentrations), C-peptide, FSH, LH, testosterone, histamine, prostaglandins (PG) A + E, PG F2, glucose and pH, as well as decrease of excretion of homovanillic acid (HVA), vanillyl mandelic acid (VMA), normetanephrine (NMN) and MN-E, NMN:NE. On recovery day 14 concentrations of E, NE, BE, STH, AC, cAMP, cGMP, FFA as well as E and dopamine excretion remained elevated while concentrations of T3, PL, FT, LT, testosterone PG A + E, PG 2 and excretion of MN, HVA, VMA, MN:E remained decreased, while other parameters returned to the normal.

[The significance of pregnancy-induced ketonuria in sheep and goats]

The last third of pregnancy in sheep and goats is characterized by a considerable reduction in the volume of the rumen. When the animal is carrying more than one fetus there is thus a latent ketosis caused by starvation. A discrete hypoglycemia is in close correlation to this. If other special factors like increasing age of the pregnant animal, chronic liver disease, unbalanced nutrition containing too little carbohydrates are also present, the latent starvation ketosis can give rise to an acute gestation ketosis. The clinical picture is described in detail and contrasted with the gestation hypocalcemia. Furthermore, the parameters relevant to laboratory diagnosis will be discussed.

Urinary excretion of a glucose-containing tetrasaccharide. A parameter for increased degradation of glycogen

The urinary excretion of a glucose-containing oligosaccharide, Glc alpha[1-6Glc alpha[1-4Glc alpha[1-4Glc, (Glc4) has been measured in various physiological and pathological conditions. The Glc4 content of 24 h samples from the same individual was relatively constant, whereas 2 h samples showed up to 4-fold variations in Glc4 concentration. This variation is associated mainly with increased excretion of Glc4 after meals. A carbohydrate-rich diet, starvation or a protein-rich diet, and intense physical activity all affected the urinary excretion of Glc4. Both oral and intravenous administration of glycogen in a Rhesus monkey resulted in increased excretion of Glc4. When Glc4 itself was injected intravenously in small amounts renal clearance was rapid and complete. In contrast, injection of a larger amount resulted in incomplete (approximately 10%) renal clearance, probably due to uptake and metabolism of the oligosaccharide. In patients with glycogen storage diseases, certain malignancies, and pancreatitis, 24 h urinary Glc4 excretion exceeded the normal range. The diagnostic implications of these observations deserve evaluation. The results presented suggest a need for standardization of nutritional status and physical activity when monitoring urinary Glc4 excretion for diagnostic purposes.

Protein and substrate metabolism during starvation and parenteral refeeding

1. Healthy male volunteers underwent 10 days of hospitalized protein-calorie starvation and a subsequent 10 day repletion phase with complete intravenous nutritional support (IVF). Non-protein calories were provided as either all D-glucose or as 50% D-glucose/50% lipid. 2. In comparison with starvation, whole-body protein breakdown, as assessed by [15N]glycine, [13C]leucine and urinary excretion of 3-methylhistidine (3-MH), was diminished during IVF. The administration of parenteral nutrition did not specifically suppress peripheral tissue protein breakdown, as measured by extremity 3-MH efflux. 3. Despite the differential insulin response to D-glucose/amino acid (50 +/- 6 m-units/ml) as compared with the D-glucose/lipid/amino acid regimen (25 +/- 4 m-units/ml), there was no difference in nitrogen retention between the regimens. Indirect calorimetric determinations revealed that oxidation of substrate during IVF was related to the proportion of D-glucose and lipid infusion.

Effect of starvation on biochemical indices of renal function in the rat

The effect of starvation on urinary output and biochemical indices of renal function was investigated in rats. Starvation resulted in a marked fall in water intake. Urinary output paradoxically increased during the first day following starvation, but fell dramatically thereafter. Urinary creatinine excretion and creatinine clearance fell markedly, but plasma creatinine concentration did not alter. Plasma urea concentration and urinary urea excretion fell. Plasma sodium concentration increased, whilst plasma potassium concentration did not alter; urinary sodium and potassium excretion fell. Plasma bicarbonate concentration fell marginally, but the anion gap increased to a greater extent. Following re-feeding, water intake and urine output increased, as did urinary creatinine excretion and creatinine clearance. Plasma urea and urinary urea concentrations, as well as sodium and potassium excretion, increased. Plasma bicarbonate increased and the anion gap decreased. These indices improved within 2 days of re-feeding and were restored to normal in 5 days.

Urinary profiles of organic acids and volatile metabolites during the starvation process in rats

Capillary gas chromatographic procedures were used to quantify the volatile and acidic compound profiles in the urinary samples of Sprague-Dawley rats during the starvation and refeeding periods. Numerous metabolites, identified through mass spectrometry, showed significant variations due to these physiological processes. Correlations are attempted with the previously studied biochemical processes in diabetic animals.

Use of urinary C-peptide to estimate insulin secretion during starvation

The usefulness of measurements of urinary C-peptide excretion in indirectly assessing integrated insulin secretion during starvation was studied in eight obese subjects during a 72-h fast. Blood and urine samples were collected at 12-h intervals for measurement of insulin and C-peptide immunoreactivity. After 60 h, serum insulin and plasma C-peptide levels declined 47% and 37%, respectively, and the values were highly correlated (r = 0.8; P less than 0.001). By 72 h, urinary C-peptide excretion had declined to 70% of the level in the first 12-h period. The urinary clearance of C-peptide was not altered by starvation. A highly significant correlation was found between urinary C-peptide and C-peptide secretory rate (P less than 0.001). The molar ratio of plasma C-peptide to insulin remained constant during the fasting period. These data indicate that basal insulin secretion can be added to the list of physiological conditions in which beta-cell secretion can be effectively evaluated by urinary C-peptide measurement.

Orotic acid excretion during starvation and refeeding in normal men

The effects of acute food deprivation and subsequent refeeding on urinary orotic acid excretion were examined in nine healthy adult male subjects. During inpatient metabolic ward conditions, the volunteers were fed a nutritionally complete, pyrimidine- and purine-free diet for three days and subsequently underwent a ten-day fast followed by a ten-day period of refeeding by total parenteral nutrition. Mean daily excretion of 4.33 +/- 0.23 mg (2.77 +/- 0.12 mg/g creatinine) of orotic acid during the enterally fed state was significantly reduced (mean 46 +/- 5%) in all subjects during starvation. This reduction in the excretion of orotic acid during starvation is more likely related to a lowered rate of production and utilization. The starvation adaptation of orotate excretion occurred more rapidly than did the decrease in urinary nitrogen loss. All subjects showed an increase (mean 48 +/- 14%) in the excretion of orotic acid during the first day of refeeding which continued throughout the refeeding phase. A significant positive correlation was shown between the daily orotic acid excretion and nitrogen intake (r = 0.98) or protein balance (r = 0.83). The response to refeeding of acutely malnourished normal male is an increase in orotic acid excretion with a decrease in whole body protein catabolism.

Effects of starvation and refeeding on the excretion of urinary steroid metabolites in mice with different genetic background

Gas chromatographic steroid metabolic profiling procedures have been applied to investigations of the effects of starvation and refeeding in mice. Urinary steroid metabolites were quantitatively followed during the starvation-refeeding experiments for mice with different genetic backgrounds. Some quantitative alterations were noted for certain congenic strains of mice. The metabolites which exhibited such quantitative variations were tentatively identified by means of combined gas chromatography-mass spectrometry.

Studies on the nephron segment with reduced sodium reabsorption during starvation natriuresis

The segment of the nephron where carbohydrate deprivation depresses Na transport leading to natriuresis was sought by a new clearance technique designed to measure segmental reabsorption in each portion of the human renal tubule. Experiments were performed during maximal water diuresis before and 4 days after carbohydrate withdrawal. Proximal reabsorption had fallen from 70 +/- 4 to 60 +/- 5 ml X min-1, p less than 0.05, by the 4th day of sugar deprivation, accounting for the natriuresis and the associated weight loss of 1.8 kg. By the 4th day of fasting, when Na excretion had returned to control levels, GFR had fallen nonsignificantly from 99 +/- 6 to 95 +/- 5 ml X min-1, while Na reabsorption along distal segments had risen. In fact, Na transport, expressed by the equivalent volumes of solute free-water generated, rose from 17.4 +/- 3.4 to 23.6 +/- 2.1 along the ascending limb of Henle's loop, and from 8.1 +/- 0.8 to 9.2 +/- 1.3 ml X min-1 X GFR-1 X 100 along the distal tubule. Thus, analysis of segmental Na transport by this method discloses that starvation natriuresis is a proximal tubular event, progressively counterbalanced by enhanced Na reclamation in more distal sites. Volume contraction and the attendant fall in GFR concur to curb delivery out of the proximal tubule which is matched by enhanced distal Na reabsorption till a new steady-state excretion is attained.

Urinary profile of L-carnitine and its derivatives in starved normal persons and ACTH injected patients with myopathy

Effect of starvation or ACTH injection on the urinary level and profile of L-carnitine and its derivatives was studied in four healthy adult men or in a normal child and two patients with myopathy, respectively. Mean total L-carnitine level in the control urine sample obtained before starvation was 389 +/- 34 mumol . man . day. The percentage distribution was found to be 46% for free-, 9% for acetyl- and 45% for acyl-L-carnitine. The acyl-L-carnitine fraction contained short-chain (65%) and long-chain acyl-L-carnitine (35%). With 2-day starvation urinary excretion of free-L-carnitine was slightly decreased and, in contrast, that of acetyl-L-carnitine was considerably increased, resulting in a significant increase in urinary total L-carnitine levels. Urinary excretion of acyl-L-carnitine was increased two-folds with starvation, but that of long-chain acyl-L-carnitine was not changed. In a normal child (female, 3.5 yr) and two patients (female, 4.5 yr and male, 23 yr) with myopathy, ACTH injection induced a significant elevation of urinary total L-carnitine levels, being mainly caused by an increased excretion of free-L-carnitine and, in the adult patient, acyl-L-carnitine. Muscle total L-carnitine contents were normal in two children but abnormally low in the adult patient, who had simultaneously very low urinary total L-carnitine level before ACTH injection. Thus, in the adult patient myopathy might be possibly caused in part by carnitine deficiency. Starvation and ACTH-induced changes in urinary level and profile of L-carnitine and its derivatives were discussed in relation to carnitine biosynthesis as well as renal regulation of carnitine clearance.

Urinary excretion of 3-hydroxy-3-methylglutaric acid in the diabetic condition

Urinary levels of 3-hydroxy-3-methylglutaric acid (HMG) were measured by gas-liquid chromatography (GLC) after an extraction with tetrahydrofuran in normal rats, streptozotocin-diabetic rats and starved rats. The analysis was also carried out in the urine of three diabetic patients after suspending the insulin treatment. Detectable amounts of HMG are excreted in urine by normal humans and rats and such an excretion increases in the diabetic condition. Starved rats present only traces of HMG in the urine.

Effects of liver damage on ketone-body production and nitrogen balance in starved rats

The metabolic effects of intraperitoneal administration of carbon tetrachloride (1ml/kg) were studied in starved rats. The most notable change in circulating substrates was an 80% fall in ketone-body concentrations, which was associated with the doubling of urinary nitrogen losses. The results demonstrate the importance of starvation ketosis in permitting fat mobilization to decrease effectively protein losses during starvation.

A simple technique to estimate severity of stress

A simple procedure to estimate stress has been developed based upon 24 hour urine urea nitrogen excretion. This catabolic index partitions total urea excretion into that resulting from dietary protein intake and obligatory urea excretion and that due to an increase in endogenous protein catabolism: catabolic index equals 24 hour urine urea nitrogen excretion - (0.5 dietary nitrogen intake + 3 grams) where an index of less than zero represents no significant stress; an index of zero to 5, moderate stress, and an index greater than 5, severe stress. In 111 persons, significant differences were noted in the catabolic index, reflecting varying degrees of stress, nutrient intake and nutritional status. The catabolic index may have useful diagnostic and treatment applications.

Factors affecting amino acid induced orotic aciduria in rats

Administration of individual amino acids is known to induce an orotic aciduria. The present studies show that the induction of orotic aciduria by glycine is highly influenced by stage of digestion of the test animal and the nitrogen content of the test diet. Short term fasting for 24 hours prevented glycine induced orotic aciduria. However, longer term fasting for 1, 3, 5, or 7 days resulted in a return in the ability of glycine to stimulate pyrimidine biosynthesis. The maximum induced orotic aciduria occurred after 3 days of fasting. The ability of glycine to induce orotic aciduria in the fed rat was also dependent on the dietary protein content. Glycine injections were unable to elicit an orotic aciduria in rats fed a protein-free diet. Addition of increasing quantities of nitrogen to the basal diet resulted in a proportional increase in glycine induced orotic aciduria.

Metabolic acidosis after hyperalimentation with casein hydrolysate. Occurrence in a starved patient

A 29-year-old woman with short bowel syndrome and prolonged starvation developed hyperchloremic metabolic acidosis after initiation of hyoeralimentation with a casein hydrolysate solution. The acidosis was not due to bicarbonate loss but was associated with diminished ability of the kidney to increase urinary acid excretion, particularly titratable acidity. Supplemental parenteral bicarbonate administration was necessary for two weeks until urinary acid excretion rose to normal.

The role of potassium in the control of ammonium excretion during starvation

Administration of KC1 0.5 mmol/kg/day to subjects undergoin prolonged starvation reduced daily urinary ammonium and beta-hydroxybutyrate excretion by one-third. These changes were accompanied by an improvement in potassium balance and an increased rate of chloride excretion. A similar fall in ammonium excretion occurred in a second group of subjects after administration of KHCO3 0.5 mmol/kg/day. Ketone body and bicarbonate excretion remained unchanged in this group while potassium balance improved. In both the first and second groups urine pH fell significantly as the rate of excretion of urinary buffer (ammonium) decreased. When the dose of KHCO3 was increased to 1.5-2.0 mmol/kg/day in fasting subjects, the urine was alkalinized, and ammonium excretion fell to negligible levels, resulting in nitrogen sparing of 2.0 g/day. The results indicate that one-half of the increase in ammonium excretion observed in starvation is due to potassium deficiency. Nitrogen wastage caused by losses of urinary ammonium during starvation can be virtually eliminated by potassium supplementation and urinary alkalinization. The decrease in beta-hydroxybutyrate excretion after potassium chloride administration was not caused by a fall in the rate of nonionic diffusion of this organic acid related to the reduction in urine pH. The reason for the fall in beta-hydroxybutyrate excretion is not apparent, though it was associated with an increase in chloride excretion.

The breast cancer discriminant: effect of age, obesity, hirsutism, starvation, and changes in adrenocortical and gonadal activity

The relationship between 17-oxogenic steroid excretion and the urinary output of certain 17-oxosteroids has been widely used to select women with metastatic breast cancer for ablation of endocrine organs. In this report, the effect of factors other than breast cancer on the ratio of androsterone plus aetiocholanolone to the 17-oxogenic steroids in urine is examined. For 83 normal women the mean value of the ratio was 0·351 ± 0·121 (s.d.). In menstruant women the ratio did not correlate with oestrogen excretion, and was little affected by increasing age, the taking of oral contraceptive tablets, obesity, and the presence of reversible amenorrhoea. Factors causing a marked reduction in the ratio were the absence of functional ovaries (47 women, mean ratio 0·116 ± 0·066), food deprivation (15 obese women, mean decrease by the 9th day of starvation, 53·4 ± 11·7%), and adrenocortical stimulation (14 women, mean decrease on day 2 of corticotrophin infusion, 52·0 ± 17·0%). Suppression of adrenocortical function with dexamethasone treatment caused no systematic change in the value of the ratio, and hirsutism was associated with a significant increase (67 women, mean value 0·447 ± 0·165). The variability of the ratio from day to day in individual women (coefficient of variation, 20·7%) suggests that it is inadvisable to select patients for treatment on the basis of measurements made on a single 24 h sample of urine.

The effects of prolonged starvation and refeeding of 24-hr. urinary insulin levels in obese subjects

Six obese patients, three men and three women, underwent a period of prolonged total starvation with subsequent refeeding. During starvation 24 hr. urinary insulin excretion fell in five of the six patients, and reached abnormally low values in four. On refeeding there was an immediate rise in urinary insulin excretion in all the patients and in four abnormally high levels were reached. After the initial rise the amounts of urinary insulin again fell despite continued and increasing calorie intake, and in three patients returned to the previously low levels. It is suggested that on refeeding there is preferential release of recently formed 'pro-insulin' from a pancreas depleted of normal insulin stores by starvation, and that restoration of a normal pattern of insulin secretion can occur only after normal pancreatic insulin stores have been repleted. A striking difference in response to starvation was observed between men and women.

The urinary excretion of aromatic acids by starved sheep

1. Four wether sheep were maintained on a diet of hay for 2 weeks and then starved for a period of 4 days.

2. Immediately before and during starvation the urinary excretion in the following fractions was determined: hippuric acid, creatinine, total diethyl ether-soluble acids of hydrolysed and unhydrolysed urine, total aromatic acids in hydrolysed and unhydrolysed urine and the proportion of the former present as benzoic and phenylacetic acids.

3. A method for determining the benzoic acid content of light petroleum extracts of urine has been developed and is described.

4. Starvation had little effect on the urinary excretion of phenylacetic acid or creatinine, but during the first 2 days of starvation there were large decreases in the excretion of all the other urinary fractions studied.

5. Of the fractions examined, 43% of the diethyl ether-soluble acids of hydrolysed urine and 42% of those of unhydrolysed urine were of exogenous origin; 76% of the total urinary aromatic acids were of exogenous origin. Partition of the aromatic acids in the urine of two of the four sheep indicated that the reduction in aromatic acid excretion on starvation was completely accounted for by the decline in benzoic acid output. Almost all the hippuric acid (97%) was of exogenous origin.

6. These results have been compared with the urinary output of aromatic acids by nonruminants when fasted, and possible reasons for the relatively large amounts of phenylacetic acid found in the urine of starved sheep have been discussed.