Reproductive Endocrine Unit and National Center for Infertility Research, Massachusetts General Hospital, 55 Fruit Street BHX 5, Boston, MA 02114, USA
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Abstract |
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Key words: aetiology/hypothalamic amenorrhoea/neuro-endocrine/recovery
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Introduction |
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The ability of most women to retain normal menstrual cycles in the setting of stress, weight loss, or exercise suggests that women who develop HA have an underlying susceptibility to amenorrhoea. Previous studies indicate that menstrual patterns after menarche (referred to subsequently as primary menstrual function) might be linked to the development of HA later in life. One study of 262 patients with secondary amenorrhoea found menstrual irregularities prior to the onset of amenorrhoea in 1020% of patients who developed HA, but found no evidence of prior menstrual irregularities in women with amenorrhoea related to Cushing's syndrome, hypothyroidism, Sheehan's syndrome, pituitary tumours, or Asherman's syndrome (Reindollar et al., 1986). Other work indicates that athletes with prior menstrual irregularities are more susceptible to developing amenorrhoea than those with normal cycles at baseline (DeCree, 1998
).
Regardless of aetiology, HA is associated with a number of neuro-endocrine abnormalities involving the hypothalamic GnRH pulse generator. Some studies report a lower mean frequency of LH pulses in HA patients than in normally cycling women (Khoury et al., 1987; Berga et al., 1989
), while previous work, including our own, has demonstrated a broader neuro-endocrine spectrum ranging from complete absence of LH pulsations to normal-appearing secretion patterns (Reame et al., 1985
; Santoro et al., 1986
; Perkins et al., 1999
). Furthermore, LH secretion patterns often vary within an individual over time (Reame et al., 1985
; Santoro et al., 1986
; Perkins et al., 1999
) in the absence of clinical change or menstrual resumption.
Because the duration of amenorrhoea influences the likelihood that a patient will develop osteopenia (Biller et al., 1991), the probability of recovering menses spontaneously is central to issues of treatment. Large longitudinal follow-up studies of 90240 patients with HA related to weight loss have shown recovery rates ranging from 33% after 3 years (Nakamura et al., 1985
) to 72% after 6 years (Hirvonen, 1977
). Recovery of spontaneous menses following anorexia nervosa range from 56% after 6 years in an adult population (Hirvonen, 1977
), to 68% after 1 year in an adolescent population (Golden et al., 1997
). The only published follow-up of psychogenic and idiopathic HA cites 6 year recovery rates of 72 and 61% respectively (Hirvonen, 1977
). Relationship of menstrual recovery to weight recovery in previous studies has been unclear due to relatively short follow-up and possible confounding psychological factors (Brown et al., 1983
; Nakamura et al., 1985
; Kotsuji et al., 1993
). No study has yet explored the question of whether primary menstrual function or GnRH pulse patterns during amenorrhoea may predict subsequent recovery from HA.
The design of the current study allowed intensive examination of factors affecting HA development and recovery in 28 patients, and addressed the following hypotheses: (i) women who develop HA in response to inciting factors have higher rates of recovery than women who develop HA in the absence of identifiable triggers, and this recovery is associated with reversal of the inciting factor, (ii) women with regular menstrual cycles prior to developing HA have a higher recovery rate than those who never established regular menstrual cycles, and (iii) women with normal-appearing LH secretion patterns have a higher recovery rate than women with highly abnormal patterns of LH secretion.
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Materials and methods |
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Baseline sampling study
Pulsatile LH secretion was assessed from frequent sampling studies in which blood was sampled every 10 min for 824 h. Two studies, which occurred prior to 1982, used a 20 min blood-sampling interval but were identical in all other respects. Plasma LH, FSH, oestradiol and progesterone concentrations were measured by radioimmunoassay, as previously described (Crowley et al., 1980; Filicori et al., 1984
), and assay methodologies remained stable over the 20 year duration of the study. All samples from an individual study were measured in the same assay. The intra-assay coefficient of variation (CV) was estimated for each study by replicate measurements of a plasma pool from that study patient.
Data analysis
Pulses were determined using a previously validated modification of the Santen and Bardin method (Santen and Bardin, 1973; Hayes et al., 1999
). The amplitude was calculated as the difference between the peak and the preceding nadir for each pulse. Undetectable values were assigned the lowest measurable assay values. A pulse was defined as a peak consisting of at least two points, in which the highest point met the criteria of 2 IU/l and three times the intra-assay coefficient of variation (%CV) above the nadir point, and a second point met at least one of those criteria. The frequency was expressed per 24 h. Values obtained for study subjects were compared with values for the early follicular phase (EFP) in 15 normally cycling women described previously (Filicori et al., 1986
; Hall et al., 1992
). Primary data for control subjects were obtained and re-analysed according to the criteria used in this study. Values from the EFP of a normal cycle were used for comparison because the low oestrogen and progesterone concentrations seen in HA most closely match the hormonal conditions present in the EFP of a normal menstrual cycle.
Longitudinal follow-up
Subject contact and data collection
From a pool of 45 women who completed baseline studies, 28 women participated in follow-up studies, 13 women could not be located, three women declined participation, and one died of an unrelated cause prior to follow-up. Participating subjects were contacted via letter and agreed to answer a three-part phone interview (n = 27) and/or questionnaire (n = 21) which addressed the topics of menstrual history, current menstrual function, pregnancy history, diet and exercise history, and eating disorder history (Table I). Examples of questions asked include: `Do you attribute any cause to losing your periods?' and `Have you ever been diagnosed with, or felt that you had an eating disorder, either anorexia, bulimia, or binge eating disorder?' Further data was gathered from subjects' hospital medical records, after informed consent was obtained.
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Primary menstrual function
Each subject was also assigned to a category of primary menstrual function, either primary amenorrhoea, oligomenorrhoea, or normal menarche. Primary amenorrhoea was defined as a complete absence of spontaneous menses. Oligomenorrhoea was defined as the achievement of menarche between ages 10 and 18, followed by an irregular cycle pattern with an average cycle duration of >35 days (Speroff et al., 1994). Normal menarche was defined as the achievement of menarche between ages 10 and 18, followed by a regular cycle pattern with cycles averaging between 21 and 35 days in length prior to the development of HA (Speroff et al., 1994
).
Neuro-endocrine pattern
Each subject received a neuro-endocrine classification based on the pattern of pulsatile LH secretion during her baseline study. LH secretion patterns were analysed and classified into the following categories as previously described (Perkins et al., 1999): (i) apulsatile, defined as the absence of LH pulsations, (ii) low amplitude, defined as a normal LH pulse frequency but a mean amplitude greater than one standard deviation below the mean amplitude in normal EFP controls (15.85% of a normal population will fall within this group), (iii) low frequency, defined as a normal mean LH pulse amplitude but an LH pulse frequency greater than one standard deviation below the mean frequency in normal EFP controls, (iv) low frequency/low amplitude, defined as both frequency and amplitude of LH pulses more than one standard deviation below the means in normal EFP controls, and (v) unclassified, defined as both frequency and amplitude of LH pulses within the normal range for women in the EFP.
Recovery
Recovery of normal menstrual function was defined as the occurrence of regular cycles with cycles averaging between 21 and 35 days (Speroff et al., 1994). Women who achieved oligomenorrhoea (average intermenstrual interval >35 days) following a period of complete amenorrhoea were not considered recovered.
Data analysis
Each parameter (causal aetiology, primary menstrual function, and neuro-endocrine pattern) was analysed with respect to the resumption of normal menstrual function. Fisher's exact test was used to determine the significance of intergroup differences in recovery rates and (homoscedastic) t-tests were used to determine the significance of intergroup differences in physical/hormonal parameters. Values are expressed as the mean ± SEM unless specified, and the two-sided 0.05 level is considered significant unless otherwise noted.
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Results |
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Aetiology
Six of the 28 women (21%) met the criteria for stress/weight loss (Figure 1). Four developed HA coincident with both stress and weight loss, one subject developed HA coincident with stress alone, and one subject developed HA coincident with weight loss alone. The mean weight loss achieved was 12.7 ± 4.1 kg, and the mean minimum BMI was 19.1 ± 0.4 kg/m2. Stress was related to parental death in two cases, work or school difficulties in two cases, and family difficulties in one case.
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Seven subjects (25%) could identify no factor that contributed to the development of amenorrhoea, and were assigned to the idiopathic category.
Primary menstrual function
Two subjects (7%) had primary amenorrhoea, and 26 subjects had secondary amenorrhoea, which was further subdivided into the categories of oligomenorrhoea (n = 9; 32%), and normal menarche (n = 17; 61%) (Figure 2). The mean age of menarche, excluding subjects with primary amenorrhoea, was 13.7 ± 0.6 years, with a range of 1117 years.
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Aetiology
All subjects whose onset of HA correlated with stress/weight loss resumed normal cycling (100% recovery). The stress and/or weight loss that precipitated HA resolved prior to menstrual resumption in all cases.
Four recoveries were associated with successful pregnancies. Two recoveries, which occurred in normal or overweight subjects, occurred in the absence of weight gain. Two recoveries, which occurred in underweight subjects, occurred coincident with post-partum weight gains of 4.5 and 13.2 kg respectively.
Nine of the 15 women (60%) who suffered from an eating disorder recovered normal menstrual function, three had some recovery of the hypothalamicpituitaryovarian axis but did not recover normal cycling patterns, one recovered normal cycles but relapsed into HA, and two remained completely amenorrhoeic. There was no difference in recovery rates between women with subclinical versus clinical eating disorder syndromes. In those women who recovered normal menstrual function, six recoveries were associated with weight gain alone (mean weight gain 10.2 ± 1.2 kg), and three recoveries were associated with a pregnancy during which patients regained weight and maintained this weight 6 months after pregnancy (mean weight gain 3.5 ± 0.4 kg). Of the three subjects who had some menstrual bleeding but did not achieve regular cycles, two are weight and symptomatically recovered, and one is currently underweight (BMI = 17.0 kg/m2). The subject, who recovered then relapsed, maintained regular cycles for 2.5 years while undergoing fluoxetine treatment for depression but ceased cycling after treatment was discontinued. Of the two amenorrhoeic subjects, one is still symptomatic and underweight (BMI = 15.4 kg/m2), and the other is mildly symptomatic and weight-recovered within the past year. Non-recovered subjects were not significantly thinner at the time of follow-up than recovered subjects (mean BMI of non-recovered = 20.0 ± 1.3 kg/m2; mean BMI of recovered = 22.0 ± 0.6 kg/m2).
Only two of the seven subjects (29%) with idiopathic HA recovered menstrual function (Table II). One subject recovered following several months of continuous treatment with pulsatile GnRH, and the other recovery occurred without obvious contributing factors.
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Baseline neuro-endocrine pattern
At follow-up, three of three (100%) subjects with unclassified patterns, nine of 13 (69%) subjects with low frequency patterns, three of five (60%) subjects with a apulsatile patterns, three of five (60%) subjects with low amplitude/low frequency patterns, and none of two (0%) subjects with low amplitude patterns recovered spontaneous menstrual function. No neuro-endocrine pattern conferred prognostic significance. Mean LH for the unclassified group was 22.1 ± 7.0 IU/l, significantly higher (P < 0.05) than mean LH values in the low frequency, low frequency/low amplitude, and apulsatile groups (mean LH = 5.7 ± 1.4 IU/l, 3.6 ± 0.7 IU/l, and 5.5 ± 2.8 IU/l for low frequency, low frequency/low amplitude, and apulsatile respectively).
Association of aetiology and neuro-endocrine pattern
Eating disorder and stress/weight loss aetiologies showed a trend toward association with a low frequency LH pulse pattern (P = 0.06), when compared with idiopathic aetiology. No association was seen between idiopathic aetiology and any particular pattern of LH secretion.
Pregnancy follow-up
Pregnancy follow-up data was available for 26 subjects. Twenty-two subjects attempted pregnancy, and 21 were successful in conceiving and carrying at least one pregnancy to term. Eighteen subjects underwent ovulation induction including clomiphene citrate, pulsatile GnRH, or gonadotrophin therapy to conceive their first children. Three subjects recovered from HA prior to attempting conception, and were able to conceive their first children spontaneously. Four subjects who resumed menstrual function following their first pregnancies later went on to conceive spontaneously.
Seven of the 18 subjects (39%) who underwent ovulation induction achieved menstrual recovery following a successful pregnancy. Five recoveries were associated with sustained weight gains in previously underweight subjects. Two recoveries, which occurred in normal or overweight subjects, were not associated with weight gain.
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Discussion |
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The reasons often given by patients to explain voluntary weight loss are health and cosmetic improvement, but recent work points to a higher level of eating pathology in amenorrhoeic dieters than previously suspected. Several studies have reported higher scores on scales of eating disordered behaviour accompanying dietary restriction in women with HA (Warren et al., 1994; Laughlin et al., 1998
). Measures of eating disordered behaviour were not obtained in our population at the time of diagnosis. However, the discovery that 54% of our population had a recent or remote history of an eating disorder, although none felt that she had an active eating disorder at the time of baseline study, raises the issue of hidden nutritional contributions to HA. Because correcting nutritional insults and pathological eating behaviour in the HA population has important prognostic implications, clinicians should seek evidence of subtle eating pathology in all patients presenting with HA.
In this study, 71% of women who developed HA following weight loss, an eating disorder, or stress recovered normal menstrual function, while only 29% of women with idiopathic HA recovered. Reversal of inciting conditions (weight loss, eating disorder, stress) occurred prior to menstrual resumption in all subjects, and 83% of subjects who returned to baseline weight and psychological functioning resumed menstruating. Thirty-nine per cent of subjects who had a successful pregnancy resumed cycling shortly thereafter, slightly lower than previously published rates (Lewinthal et al., 1987). However, pregnancy was accompanied by sustained weight gain in all underweight subjects who resumed cycling, which may indicate that weight recovery is necessary for pregnancy-associated menstrual recovery in underweight subjects. We found a higher rate of menstrual recovery following weight gain (78%) than previously reported rates, which ranged from 3368% (Nakamura et al., 1985
; Golden et al., 1997
). The reason may be the longer duration of follow-up in the current study, as the mean duration of amenorrhoea in our population was 7.5 ± 1.2 years, and follow-up in other studies ranged from 13 years. Although recovery rates in this study were higher than previously reported, not all weight and psychologically recovered subjects resumed menstruating, indicating that reversal of inciting factors is necessary but not always sufficient for menstrual recovery in HA.
Underlying physiological differences may interplay with environmental insults in the development of and recovery from HA. The rate of prior menstrual dysfunction in our HA patients was 39%, higher than rates found in previous work (1020%), and quite different from the insignificant rates of menstrual dysfunction seen in women who became amenorrhoeic secondary to other medical conditions (Reindollar et al., 1986). However, recovery rates did not differ between women with oligomenorrhoea compared with women who had normal menarche. Women with primary amenorrhoea showed a trend toward lower recovery rates, the significance of which might be better determined with larger study groups.
LH pulse patterns ranging from a complete absence of LH pulsations to normal-appearing patterns of secretion were not associated with statistically different rates of recovery. This may imply that the majority of abnormalities represent different time points in a single illness, rather than different illnesses. Previous work has shown that single individuals may manifest distinct patterns of LH secretion when studied at different time points during their illnesses without any associated clinical change or menstrual resumption (Reame et al., 1985; Perkins et al., 1999
).
A decreased frequency of LH pulsations, the most frequently described abnormality in this population, was associated with eating disorder and stress/weight loss aetiologies. This is consistent with previous work demonstrating an association between decreased LH pulse frequency and weight loss-related HA (Khoury et al., 1987; Berga et al., 1991
), as well as work demonstrating that strict dieting decreases the frequency of LH pulsations in normal volunteers (Pirke et al., 1989
).
This study had several limitations. Because it was a retrospective study, all dates, measurements, and attributions are based on subjects' recollections. However, the retrospective data obtained in interviews correlated well with both questionnaire data and with information from hospital records obtained at the time of presentation. The relatively low rate of follow-up (62%) introduces the possibility of selection bias. However, participating subjects did not differ from non-participating subjects in age at amenorrhoea, duration of amenorrhoea at presentation, or BMI. Finally, the small sample sizes may mask the prognostic significance of certain variables.
Despite its limitations, this study provides insight into the common aetiologies and predictors of recovery in HA. Aetiology at the time of presentation is the most important predictor of menstrual recovery, with idiopathic HA conferring a worse prognosis. The most common aetiological factor is weight loss, either alone or with concurrent psychological factors. In stress, weight loss, or eating disorder-related HA, rates of recovery can exceed 80% when precipitating factors are reversed. Reversal of precipitating factors in these cases appears to be necessary but not sufficient for recovery. HA in women who present without precipitating factors may represent a different disorder, as recovery rates were <30% and there was no association with decreased frequency of LH pulsations. Further work is needed to elucidate potential genetic differences underlying the spectrum of HA.
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Notes |
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References |
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Submitted on March 28, 2001; accepted on June 14, 2001.