Prediction of ovulation by urinary hormone measurements with the home use ClearPlan Fertility Monitor: comparison with transvaginal ultrasound scans and serum hormone measurements

The timing of sexual intercourse in relation to ovulation strongly influences the chance of conception. Daily serum LH measurements or transvaginal ultrasonography are not practical to determine ovulation in consecutive cycles for an individual. A prospective study was initiated to test the home use performance of the ClearPlan Fertility Monitor (CPFM) in ovulation prediction compared with transvaginal ultrasonography and serum hormone measurements. A total of 53 women aged 18-39 years with a normal uterus and at least one ovary, cycle length between 21-42 days and not using medication which interferes with ovarian function contributed 150 cycles for analysis. One cycle was anovulatory and no LH surge, indicating peak fertility, was detected by the monitor. Of the remaining 149 cycles, 135 (90.6%) had a monitor LH surge and ultrasonographically confirmed ovulation. Ovulation was detected in 91.1% of cycles during the 2 days of CPFM peak fertility. Ovulation was observed in 51.1% of cycles 1 day and in 43.2% of cycles 2 days after the surge in serum LH. Ovulation never occurred before CPFM peak fertility or the serum LH surge day. CPFM can help women who desire pregnancy to time intercourse. It may also have potential as a diagnostic aid and for monitoring the treatment of infertility.     

Purified urinary follicle stimulating hormone induces different hormone profiles compared with menotrophins, dependent upon the route of administration and endogenous luteinizing hormone activity

The effects of treatment of patients with gonadotrophin-releasinghormone analogue (GnRHa) combined with purified follicle stimulatinghormone (FSH) for in-vitro fertilization (IVF) were investigatedin detail to determine the influences of different administrationroutes and the degree of suppression of luteinizing hormone(LH). Responses to exogenous gonadotrophins were studied ininfertile women (n = 60) with normal menstrual rhythm whoseendogenous gonadotrophin activity was suppressed using a GnRHain a long protocol. They were randomized to receive i.m. administrationof human menopausal gonadotrophins (HMGim, Pergonal) or purifiedfollicle stimulating hormone (FSH, Metrodin High Purity) administeredeither i.m. (MHPim) or s.c (MHPsc). Responses were assessedby measuring plasma FSH, LH, oestradiol, testosterone and progesterone.After stimulation day 4, the MHPsc group showed significantlyhigher circulating concentrations of FSH than either the MHPimor HMGim group. However, the HMG group showed significantlyhigher oestradiol concentrations after stimulation day 5 thaneither MHP group. The differences in circulating oestradiolconcentrations in the MHP-treated patients appeared to be stronglyinfluenced by the mean circulating concentrations of LH in thefollicular phase. The patients who showed mean follicular phaseLH concentrations of <1 IU/1 showed longer follicular phases,lower circulating oestradiol and testosterone concentrationsand also lower follicular fluid concentrations of oestradioland testosterone, indicating a reduction in the normal follicularmetabolism of progesterone to androgens and oestrogens underthese conditions. This group of patients also showed longerfollicular phases, which may have consequences for future clinicalmanagement.     

Induction of ovulation in rabbits with pure urinary luteinizing hormone and human chorionic gonadotrophin: comparison of oocyte and embryo quality.

Thirty-six 18-week-old nulliparous does were stimulated with a single dose of 25 IU pregnant mare serum gonadotrophin (PMSG). Ovulation was induced 48 h later with 50 IU luteinizing hormone (LH) (18 does) or 50 IU human chorionic gonadotrophin (HCG) (18 does) in order to determine the effects of pure urinary LH and HCG on the quality of oocytes and embryos. Nine does were mated in each group. The does were slaughtered 24 h after induction of ovulation to recover oocytes and 48 h after mating to recover embryos. The number of haemorrhagic, preovulatory and luteinizing follicles per ovary were recorded. The quality of oocytes and embryos recovered were evaluated. No significant differences in the number of haemorrhagic follicles (blood follicles without stigma), preovulatory and luteinizing follicles were observed between LH and HCG groups. LH has a selective action, which could permit the acquisition of better quality oocytes. Although the fertilization rate was similar in both groups (LH versus HCG), the percentage of degenerate embryos (grade 5) was lower for the LH (3%) than the HCG (13%) groups.     

Endocrinology: Triggering of ovulation using a gonadotrophin-releasing hormone agonist does not prevent ovarian hyperstimulation syndrome

A total of 24 women with primary or secondary infertility dueto oligo- or anovulation, were treated with human menopausalgonadotrophin (HMG). In 48 cycles, we used a gonadotrophin-releasinghormone agonist (GnRHa) nasal spray (buserelin) to induce apre-ovulatory endogenous luteinizing hormone (LH) surge. In44 cycles, there was a rapid rise of the serum LH concentrationwithin 8 h from the first administration of GnRHa. One patientwith pituitary hypogonadotrophic amenorrhoea showed a weak orno response in four treatment cycles. Conception occurred in10 cycles (pregnancy/cycle (P/C) index = 22.7%), four of whichended in a spontaneous abortion and six of which are ongoingpregnancies. In 27 cycles, there was an increased risk for ovarianhyperstimulation syndrome (OHSS), defined as more than threefollicles 18 mm in diameter and/or serum oestradiol > 1200pg/ml. Three of these treatment cycles gave rise to the developmentof moderate OHSS in the absence of exogenously administeredhuman chorionic gonadotrophin, two being conception cycles.     

Controlled preparation of the endometrium with exogenous oestradiol and progesterone: a novel regimen not using a gonadotrophin-releasing hormone agonist.

In women having inactive ovaries, controlled preparation of the endometrium has been achieved with exogenous oestradiol and progesterone. We report on the feasibility and practicality of using a similar regimen for timing transfers of cryopreserved embryos in women whose ovaries have not been suppressed. A total of 91 women having cryopreserved embryos from previous in-vitro fertilization (IVF) attempts received 4 mg/day of oestradiol valerate, starting on cycle day 1 of spontaneous (n = 85) or induced (n = 6) menstruation. A single blood sample was obtained on cycle day 14 for the measurement of plasma progesterone, oestradiol and luteinizing hormone (LH). Vaginal administration of micronized progesterone (300 mg/day) was started on day 15. Cryopreserved embryos were transferred on day 17 or 18 provided that day 14 plasma progesterone remained < or = 0.5 ng/ml, thereby confirming the absence of spontaneous ovulation prior to the administration of exogenous progesterone. Out of 91 cycles studied, plasma progesterone was found to be elevated (> 1 ng/ml) in only three (3.2%). Of the 88 scheduled transfers, 31 did not take place because no embryo survived thawing. In the remaining 57 cycles, 116 embryos were transferred resulting in 10 pregnancies, giving pregnancy and embryo implantation rates of 17.5 and 8.6% respectively. When a positive beta human chorionic gonadotrophin (HCG) titre was obtained, supplementation with oral oestradiol and vaginal progesterone was continued until placental autonomy was achieved. Of the 10 pregnancies, five (50%) were lost during the first trimester (biochemical, n = 1; miscarriage, n = 3; ectopic, n = 1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrinology: Effects of recombinant human follicle stimulating hormone on cultured human granulosa cells: comparison with urinary gonadotrophins and actions in preovulatory follicles

The effects of recombinant human follicle stimulating hormone(rFSH; Org 32489) have been examined in human granulosa cellsfrom ovaries obtained from women with spontaneous menses. Inthe first series of experiments the actions of rFSH on productionof oestradiol and progesterone were compared with those of urinary-derivedgonadotrophins. Recombinant FSH induced dose-dependent increasesin production of both oestradiol and progesterone which weresimilar to the effects of ’pure‘ FSH (Metrodin®)and the International Standard IS 71/223. In further studies,the actions of rFSH on oestradiol production by individual preovulatoryfollicles were investigated; rFSH increased oestradiol accumulationfrom cells obtained from follicles before the luteinizing hormone(LH) surge. In contrast, rFSH inhibited oestradiol productionby granulosa cells derived from a follicle after the onset ofthe LH surge, whereas the gonadotrophic action of growth hormonewas maintained. Following preliminary reports of the in-vivoeffects of rFSH in women, these findings provide further validationof the efficacy of rFSH in the human ovary. The results of studiesof the preovulatory follicle illustrate the experimental importanceof the availability of recombinant preparations of pure gonadotrophins,produced by recombinant technology, in the understanding ofhuman ovarian function.     

EndocrinologyHormonal profile during the follicular phase in cycles stimulated with a combination of human menopausal gonadotrophin and gonadotrophin-releasing hormone antagonist (Cetrorelix)

A third-generation gonadotrophin-releasing hormone antagonist(Cetrorelix) was used during ovarian stimulation in 32 patientsundergoing assisted reproduction, in order to prevent the prematureluteinizing hormone (LH) surge. In all patients, ovarian stimulationwas carried out with two or three ampoules of human menopausalgonadotrophin (HMG), starting on day 2 of the menstrual cycle.In addition, 0.5 mg of Cetrorelix was administered daily fromday 6 of HMG treatment until the day of ovulation inductionby human chorionic gonadotrophin (HCG). A significant drop inplasma LH concentration was observed within a few hours of thefirst administration of Cetrorelix (P<0.005). Moreover, noLH surge was detected at any point in the treatment period inany of the 32 patients. A mean oestradiol concentration of 2122±935ng/1 was observed on the day of the HCG administration, indicatingnormal folliculogenesis. Like LH, progesterone concentrationalso dropped within a few hours of the first administrationof Cetrorelix (P< 0.005). A 0.5 mg daily dose of Cetrorelixprevented a premature LH surge in all the 32 patients treated.     

Infertility: Evaluation of transvaginal sonography combined with a urinary luteinizing hormone monitor in timing donor insemination

There remains controversy as to the most accurate method ofpredicting ovulation for the timing of donor insemination. Ina prospective study based at a tertiary referral donor inseminationclinic we have assessed the ability of a urinary luteinizinghormone (LH) kit combined with vaginal ultrasonography to predictovulation for donor insemination. A total of 25 natural cycleswere monitored from the first day of the LH surge (detectedby the urinary kit). Daily transvaginal sonographic measurementof follicular size and endometrial thickness were used to predictovulation; monitoring continued until post-ovulatory changeswere seen. Transvaginal sonography combined with a urinary LHkit successfully predicted all those women who ovulated (20/25)and detected unfavourable conditions for insemination in theremaining 20% (5/25). In conclusion, where available transvaginalsonography combined with a urinary LH kit should be the methodof choice for timing donor insemination.     

Endocrinology: The role of luteinizing hormone in human follicle development and oocyte fertility: evidence from in-vitro fertilization in a woman with long-standing hypogonadotrophic hypogonadism and using recombinant human follicle stimulating hormone

To evaluate the relative importance of follicle stimulatinghormone (FSH) and luteinizing hormone (LH) in follicular developmentand oocyte fertility in the human species, the use of recombinanthuman FSH, human menopausal gonadotrophin (HMG), and very highlypurified urinary human FSH (FSH-HP) plus oestradiol valeratefor ovarian stimulation and in-vitro fertilization (IVF) werecompared in three cycles in a woman with isolated congenitalgonadotrophin deficiency who had never been treated with ovarianstimulating agents. The total number of ampoules of gonadotrophinsused was lower in the HMG treatment cycle. Ovarian responseand IVF outcome in the three treatment cycles were as follows:(i) HMG cycle: normal follicular growth, normal pattern of oestradioland inhibin through the menstrual cycle, high fertilizationrate (93%); (ii) recombinant FSH cycle: normal follicular growth,low oestradiol and abnormal inhibin, finally poor rate of fertilization(28%); (iii) FSH-HP plus oestradiol valerate cycle: normal folliculargrowth, normal pattern of inhibin and poor fertilization rate(27%). Luteal plasma progesterone concentrations were much higherin the HMG treatment cycle. This case shows that FSH is theonly factor required in order to induce follicular growth inthe human, although LH or a product derived from its actionmay assist in order to achieve full follicular maturity andoocytes capable of fertilization. Though oestradiol might havea mediatory role in the process of follicular maturation, ourresults favour a direct primary role of LH in complete maturationof the follicle.     

Endocrinology: Reduced implantation rate associated with a subtle rise in serum progesterone concentration during the follicular phase of cycles stimulated with a combination of a gonadotrophin-releasing hormone agonist and gonadotrophin

Our objective was to assess the effects of subtle increasesin serum progesterone concentration (1.0–2.0 ng/ml) onthe outcome of in-vitro fertilization (IVF), particularly onthe quality of embryos, during the follicular phase of cyclesstimulated with gonadotrophin-releasing hormone agonist (GnRHa)and human menopausal gonadotrophin (HMG). A total of 97 patientsunderwent 116 cycles of IVF and were stimulated with a combinationof HMG and GnRHa. They were divided into two groups: those witha subtle progesterone rise and those with no progesterone rise.The two groups were compared with respect to serum oestradiol,progesterone, immunoreactive luteinizing hormone (I-LH), bioactiveLH (B-LH), and results of IVF. The groups did not differ significantlyin mean age or in total dose of HMG received. On the day thathuman chorionic gonadotrophin was administered, concentrationsof oestradiol and progesterone were significantly higher inthe subtle progesterone rise cycles than in the no progesteronerise cycles. In the no progesterone rise cycles, the percentagesfor embryos beyond the 4-cell stage, grade 1 embryos, and implantationrates were significantly higher than those in subtle progesteronerise cycles. The combination of GnRHa and HMG eliminated anysignificant rise in serum I-LH or B-LH concentration duringthe follicular phase, but did not suppress the subtle rise inprogesterone. These results confirm our previous finding thata subtle progesterone rise adversely affects the outcome ofIVF. It is also suggested that a reduction in embryo qualitymay influence the lower rate of implantation in subtle progesteronerise cycles.     

Endometrial histomorphometry of trimegestone-based sequential hormone replacement therapy: a weighted comparison with the endometrium of the natural cycle.

Histomorphometric changes in the endometrium were evaluated under the effect of a trimegestone-based sequential hormone replacement therapy (HRT) regimen, and the findings were compared to those in endometrium of the natural cycle. Endometrial samples were taken from postmenopausal women who completed a randomized, double blind, dose-ranging study of oral trimegestone (0.05, 0.1, 0.25 and 0.5 mg per day) from day 15 to day 28 with continuous micronized oestradiol 2 mg daily for six treatment cycles. The HRT-treated endometrium, irrespective of the dose, had a smaller mean total glandular area, smaller average glandular diameter, smaller mean total vascular space area and diameter than the luteal phase. Stromal cellularity was similar in the four dose groups. There were reduced glandular secretions in the endometrium from the high dose group. The relative weighting of these histological parameters was evaluated by linear discriminant analysis. The weighted values were dose independent, and may therefore represent either a specific effect of trimegestone, number of days administered, or both. We have constructed an equation to assign a value for a histological parameter which determines the position on linear discriminant functions. These assigned values can be used in other sequential HRT regimens to determine the relative influence of a given progestogen on endometrial morphology in relation to different phases of the natural cycle.     

Fertilization and early embrology: The secretion of gonadotrophin-releasing hormone by peri-implantation embryos of the rhesus monkey: comparison with the secretion of chorionic gonadotrophin

Chorionic gonadotrophin (CG) is the first clear embryonic signalduring early pregnancy in primates. CG has close structuraland functional similarities to pituitary luteinizing hormone(LH) which is regulated by gonadotrophin releasing hormone (GnRH).Tostudy the regulatory mechanism of CG secretion in primate embryos,we examined the production and timing of secretion of GnRH inperi-implantation embryos of the rhesus monkey. In-vivo fertilized/developedmorulae and early blastocysts, recovered from non-superovulated,naturally-bred rhesus monkeys by non-surgical uterine flushing,were cultured in vitro to hatched, attached and post-attachedblastocyst stages using a well-established culture system. Wemeasured GnRH and CG in media samples from cultured embryoswith a sensitive radioimmunoassay and bioassay, respectively.The secretion of GnRH (pg/ml; mean ± SEM) by embryos(n = 20) commenced from low levels (0.32 ± 0.05) duringthe pre-hatching blastocyst stage to 0.70 ± 0.08 at 6–12days and 1.30 ± 0.23 at 13 days of hatched blastocystattachment and proliferation of trophoblast cells. GnRH concentrationsin culture media obtained from embryos (n = 5) that failed tohatch and attach were mostly undetectable (0.1). Samples thatdid not contain detectable GnRH failed to show detectable CG.Immunocytochemical studies, using a specific monoclonal anti-GnRHantibody (HU4H) as well as polyclonal antisera (LR-1), revealedthat immunopositive GnRH cells were localized in pre-hatchingblastocysts (n = 4), in blastocysts (n = 2) after 5–10days of attachment and in monolayer cultures (n = 4) of well-establishedembryonic trophoblast cells. GnRH positive staining was seenonly in cytotrophoblasts but not in syncytiotrophoblasts. Similarly,cytotrophoblast, but not syncytiotrophoblast, cells of the rhesusplacenta were immunopositive. In controls, either in the absenceof antibody or in the presence of antibody pre-absorbed withGnRH, these cells failed to show stain. These observations indicate,for the first time, that an immunoreactive GnRH is producedand secreted by blastocysts during the peri-attachment periodand by embryo-derived cytotrophoblast cells in the rhesus monkey.     

Cost-effectiveness of a mild compared with a standard strategy for IVF: a randomized comparison using cumulative term live birth as the primary endpoint

BACKGROUND Conventional ovarian stimulation and the transfer of two embryos in IVF exhibits an inherent high probability of multiple pregnancies, resulting in high costs. We evaluated the cost-effectiveness of a mild compared with a conventional strategy for IVF. METHODS Four hundred and four patients were randomly assigned to undergo either mild ovarian stimulation/GnRH antagonist co-treatment combined with single embryo transfer, or standard stimulation/GnRH agonist long protocol and the transfer of two embryos. The main outcome measures are total costs of treatment within a 12 months period after randomization, and the relationship between total costs and proportion of cumulative pregnancies resulting in term live birth within 1 year of randomization. RESULTS Despite a significantly increased average number of IVF cycles (2.3 versus 1.7; P < 0.001), lower average total costs over a 12-month period (8333 versus euro10 745; P = 0.006) were observed using the mild strategy. This was mainly due to higher costs of the obstetric and post-natal period for the standard strategy, related to multiple pregnancies. The costs per pregnancy leading to term live birth were euro19 156 in the mild strategy and euro24 038 in the standard. The incremental cost-effectiveness ratio of the standard strategy compared with the mild strategy was euro185 000 per extra pregnancy leading to term live birth. CONCLUSIONS Despite an increased mean number of IVF cycles within 1 year, from an economic perspective, the mild treatment strategy is more advantageous per term live birth. It is unlikely, over a wide range of society's willingness-to-pay, that the standard treatment strategy is cost-effective, compared with the mild strategy.     

Noninvasive measurement of cardiac output in hemodialysis patients by task force monitor: a comparison with the Transonic System

Cardiovascular disease is the leading cause of morbidity and mortality in maintenance hemodialysis (MHD) patients. The Transonic (TRS; Transonic Systems, Ithaca, NY) device is frequently used for determination of cardiac output (CO) by an indicator dilution technique. The Task Force Monitor (TFM; CN Systems, Graz, Austria) has gained attention as noninvasive tool for continuous beat-to-beat assessment of cardiovascular variables, including CO by impedance cardiography. Despite its use in cardiology and intensive care settings, the TFM has yet not been validated in dialysis patients. This study compares CO measurements in 12 MHD patients by TFM and TRS. Bland-Altman and regression analysis were used. CO was measured simultaneously by TRS and TFM. Average CO was 5.4 L/min by TRS and 5.0 L/min by TFM, respectively. Bland-Altman analysis revealed no significant systematic differences between the two methods (mean difference: 0.4 L/min; SD: 0.6; p > 0.05). Linear regression analysis showed significant correlation between both techniques (r = 0.802, p = 0.002). The SD of mean individual CO values was 1.1 L/min with TRS and 0.8 L/min with TFM, respectively.CO measured by TFM and TRS does not differ significantly, thus making the TFM an attractive noninvasive tool for the continuous beat-to-beat assessment of CO in MHD patients.     

Revival of the natural cycles in in-vitro fertilization with the use of a new gonadotrophin-releasing hormone antagonist (Cetrorelix): a pilot study with minimal stimulation

Natural cycles were abandoned in in-vitro fertilization (IVF) embryo transfer, due to premature luteinizing hormone (LH) surges--and subsequent high cancellation rates. In this study, we investigated the administration of a new gonadotrophin-releasing hormone antagonist (Cetrorelix) in the late follicular phase of natural cycles in patients undergoing IVF and intracytoplasmic sperm injection (ICSI). A total of 44 cycles from 33 healthy women [mean age 34.1 +/- 1.4 (range 26-36) years] were monitored, starting on day 8 by daily ultrasound and measurement of serum concentrations of oestradiol, LH, follicle stimulating hormone (FSH) and progesterone. When plasma oestradiol concentrations reached 100-150 pg/ml, with a lead follicle between 12-14 mm diameter, a single injection (s.c.) of 0.5 mg (19 cycles) or 1 mg (25 cycles) Cetrorelix was administered. Human menopausal gonadotrophin (HMG; 150 IU) was administered daily at the time of the first injection of Cetrorelix, and repeated thereafter until human chorionic gonadotrophin (HCG) administration. Four out of 44 cycles were cancelled (9.0%). No decline in follicular growth or oestradiol secretion was observed after Cetrorelix administration. A total of 40 oocyte retrievals leading to 22 transfers (55%) was performed. In 10 cycles (25%), no oocyte was obtained. Fertilization failure despite ICSI occurred in six cycles (15%). In two patients the embryo was arrested at the 2 pronuclear (PN) stage. The stimulation was minimal (4.7 +/- 1.4 HMG ampoules). A total of seven clinical pregnancies was obtained (32.0% per transfer, 17.5% per retrieval), of which five are ongoing. Thus, a spontaneous cycle and the GnRH antagonist Cetrorelix in single dose administration could represent a first-choice IVF treatment with none of the complications and risks of current controlled ovarian hyperstimulation protocols, and an acceptable success rate.     

Clinicopathologic significance of the basal-like subtype of breast cancer: a comparison with hormone receptor and Her2/neu-overexpressing phenotypes

DNA microarray profiling studies have led to the classification of invasive breast carcinoma into luminal/estrogen receptor-positive, normal breast-like, Her2/neu-overexpressing, and basal-like types. Among these groups, the basal-like subtype is associated with the poorest clinical outcome in Western countries. To date, the clinicopathologic characteristics of the basal-like carcinomas, compared with other subtypes, have not been described in the Korean population. In this study, we used tissue microarray to examine the expression of basal cytokeratins (CK) (CK5 and CK14) and luminal CK (CK8/18), epidermal growth factor receptor, c-kit, hormone receptors (HRs), p53, and Her2/neu in 776 consecutive patients diagnosed with invasive breast carcinoma from January 1993 to December 1998 and categorized these cases into 5 subgroups (basal-like, HR-expressing, Her2/neu-overexpressing, HR and Her2/neu-expressing, and null subtypes negative for all markers), based on the immunohistochemical data. We identified cases of 114 (14.7%) basal-like, 345 (44.5%) HR-expressing, 133 (17.1%) Her2/neu-overexpressing, 61 (7.8%) HR and Her2/neu-expressing, and 123 (15.9%) null subtypes. Histologically, most basal-like breast cancers were invasive ductal carcinoma, not otherwise specified (98 cases, 86.0%), with high nuclear and/or histologic grades, and most metaplastic carcinomas (6 [75.0%] of 8 cases) were the basal-like subtype. Both basal-like and Her2/neu-overexpressing subtypes were associated with larger tumor sizes (mean, 3.6 and 3.3 cm, respectively) than the HR-expressing group (mean, 2.8 cm) (P = .001 and P = .036, respectively). Nodal stage of Her2/neu-overexpressing subtype was higher than that of basal-like subtype; however, overall stage was not different between the 2 groups (P = .010 and .123, respectively). Distant metastasis was most frequently observed in the Her2/neu-overexpressing subtype (33.8%), which was prognostically the worst subgroup of breast cancers. In contrast to previous findings from Western countries, our analyses reveal that the Her2/neu status is the most important prognostic factor of breast cancers.     

The heterogeneity of antibodies with respect to equilibrium constants: Calculation by a new method using delta functions,and analysis of the results

A method of data analysis has been developed which approximates the probability density of association constants of the reaction of hapten with antibody by a minimum number of delta functions, and alternatively, by a large number of delta functions. The method has been computerized and found able to approximate any physically possible affinity distribution.We have calculated the delta function distributions which describe known distributions of association constants and analyzed experimental data,. From 2 to 4 delta funticons we3re required to describe the probability density of Sips distributions. Not more than three delta functions were needed to describe the probability density functions of each of three antibody populations obtained from pooled antisera. These delta function distributions were found in one case to fit the data significantly more accurately than a Sips distribution. In the other two cases the fit was about the same as the Sips distribution. Affinity heterogeneity analysis using a large number of delta functions gave roughly equivalent results in terms of closeness of fit to the data to the results using a minimum number of delta functions. It is shown that binding measurements do not contain sufficient information to prove homogeneity of antibody. An analysis of factors affecting the resolution of delta functions is given.