Gilbert's syndrome (GS) is the most common cause of unconjugated hyper- bilirubinemia in the adult and its incidence has been reported to be between. 1-5% of ...
SERUM FREE FATTY ACIDS AND BILIRUBIN C O N C E N T R A T I O N DURING FASTING IN PATIENTS W I T H GILBERT'S SYNDROME AND N O R M A L CONTROLS" NICOLETTA ORZES e:', GIORGIO TAMARO "::'':',SERGIO PARCO ":"::', GIULIA BALDINI ¢'e:'e:',GIAN CARLO LUNAZZI ":'e:"::',GIAN LUIGI SOTTOCASA ":-e:'e:', MARIA ANGELA MANGIAROTTI "::"::',CLAUDIO TIRIBELLI ":" Istztuto di Patologia Generale ~, Universitd degli Studi di Trieste Laboratorio di Analisi Chimico-Cliniche ~, Istituto per l'Infanzia "Burlo GarofoIo', Trieste Dipartimento di Bioehimica, Biofzsica e Chimica delle Macromolecole ~ , Universitd degli Studi di Trieste
Gilbert's syndrome (GS) is the most common cause of unconjugated hyperbilirubinemia in the adult and its incidence has been reported to be between 1-5% of the total population '~. GS is characterized by a chronic, fluctuating unconjugated hyperbilirubinemia in the absence of overt signs of hyperhemolysis and in the presence of normal liver function tests. It has been shown that caloric restriction induces a rise in serum bilirubin levels and that this increment is significantly higher in patients with GS than in control subjects. On these grounds, the fasting-induced hyperbilirubinemia has been proposed as a diagnostic test for this syndrome'7 The mechanism(s) accounting for the serum bilirubin increment remains still poorly understood. A relationship between free fatty acids (FFA) and bilirubin plasma levels has been reported in man and in animals. In 1975, COWAN et al. 2 observed a parallel increase of FFA and bilirubin in 17 patients with myocardial infarction. Subsequently, they demonstrated that the increment in FFA serum concentration induced by fasting was correlated to that of unconjugated bilirubin 3. In 1980, NAYLOR et al. '° showed that a strict correKey-words: Bilirubin; Caloric restriction; Freefatty acids; Gilbert's syndrome.
• Presented in part at the 17th Meeting of the European Association for the Study of the Liver, G6teborg, Sweden. Supported by a grant from Ministero della Pubblica Istruzione, Roma, Italy. Nicoletta Orzes and Giulia Baldini were partially supported by grants from Regione Friuli-Venezia Giulia, 'Fondo per lo Studio e la Ricerca Scient~ca delle Malattie del Fegato:
Accepted for publication on January 13, 1987. La Ricerca Clin. Lab. 17, 61, 1987.
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lation was present between FFA and bilirubin serum concentrations during fasting in the horse. In the present paper we report on the effects of a reduced caloric intake in increasing bilirubin and FFA serum levels in normal subjects and GS patients o f both sexes. MATERIALS AND METHODS S u b j e c t s - The study includes 17 patients with GS (10 males and 7 females, age range 24-50 years) and 12 healthy volunteers (5 males and 7 females, age range 21-36 years). Diagnosis of GS was based on the demonstration of chronic unconjugated hyperbilirubinemia in the presence of normal liver function tests and in the absence of overt signs of hyperhemolysis. In all the subjects erythrocyte and reticulocyte counts, osmotic fragility and immunoelectrophoretic patterns of hemoglobin were normal. In the control subjects there was no history of liver a n d / o r hematologic diseases, alcohol intake higher than 40 g/day or drug consumption. All the subjects had a weight within the normal standards and did not receive any drug during the 2 weeks preceding the test. In female subjects, the test was performed at the 20th day of the menstrual cycle. Informed consent to participate in the study was obtained from all the subjects. R e d u c e d c a l o r i c i n t a k e t e s t - Three days after a controlled diet of 2,000 cal/day, the subjects were given a restricted diet of 400 cal/day for 48h. The subjects were outpatients and they were allowed a moderate physical activity. Blood samples were collected in the morning (at 08 °°) at times 0, 24 and 48h. Unconjugated bilirubin (mmol/1) was determined by the difference between total and conjugated bilirubin measured according to MmHAELSON et al. 9. FFA serum concentrations (mEq/1) were determined according to DUCOMBE4. The determinations were performed in triplicate within 30 rain after sample collection. D a t a a n a l y s i s - Results are expressed as mean + SEM. Statistical analysis was done by using Student's t-test for unpaired data and linear regression coeffmient. Differences with p < 0.05 were considered statistically significant.
RESULTS Table 1 reports the serum bilirubin levels at 0, 24 and 48h after caloric restriction in the 4 groups of subjects. As expected, a statistically significant difference (p< 0.01) was present between normal subjects and GS patients in the basal bilirubinemia. Caloric restriction induced in all the subjects a significant rise (p< 0.01) in bilirubin concentration at 24h. A further increment was observed in normal males and GS patients of both sexes at 48h. On the contrary, a slight decrease was found in normal females, the difference between 0 and 48h levels still remaining statistically significant (p < 0.05). The increment in serum bilirubin observed 48h after caloric restriction was significantly higher (p< 0.01) in males than in females, both normal and with GS. Table 2 reports the plasma FFA levels at the three considered time intervals in the 4 groups of subjects. No statistical difference among the groups was present at the 0 time. Caloric restriction induced an increment in FFA serum concentrations in all the subjects. Serum FFA concentrations at 24 and 48h 62
N. O R Z E S e t
al.
bilirubin s e r u m levels (mmol/l) n~
basal
24h
48h 22.9 + 3.9 ~:°
normal males
5
8.9 + 2.0
18.1 + 2 . u
n o r m a l females
7
8.4 + 1.4
14.5 + 1.0 ~
12.7 + 1.6 ~:'~
10
17.4 + 2.9
40.9 + 3.6
