Chemistry
EMP, also known as estradiol 3-normustine 17β-phosphate or as estradiol 3-(bis(2-chloroethyl)carbamate) 17β-(dihydrogen phosphate), is a synthetic estrane steroid and a derivative of estradiol. It is an estrogen ester; specifically, EMP is a diester of estradiol with a C3 normustine (nitrogen mustard–carbamate moiety) ester and a C17β phosphate ester. EMP is provided as the sodium or meglumine salt. EMP is similar as a compound to other estradiol esters such as estradiol sulfate and estradiol valerate, but differs in the presence of its nitrogen mustard ester moiety. Antineoplastic agents related to EMP, although none of them were marketed, include alestramustine, atrimustine, cytestrol acetate, estradiol mustard, ICI-85966, and phenestrol.Due to its hydrophilic phosphate ester moiety, EMP is a readily water-soluble compound. This is in contrast to most other estradiol esters, which are fatty acid esters and lipophilic compounds that are not particularly soluble in water. Unlike EMP, estramustine is highly lipophilic, practically insoluble in water, and non-ionizable. The phosphate ester of EMP was incorporated into the molecule in order to increase its water solubility and allow for intravenous administration.The molecular weight of EMP sodium is 564.3 g/mol, of EMP meglumine is 715.6 g/mol, of EMP is 520.4 g/mol, of estramustine is 440.4 g/mol, and of estradiol is 272.4 g/mol. As a result of these differences in molecular weights, EMP contains about 52%, EMP sodium about 48%, and EMP meglumine about 38% of the amount of estradiol within their structures as does an equal-mass quantity of estradiol. History
EMP was first synthesized in the mid-1960s and was patented in 1967.
Hormonal – related to the increasing amounts of estrogen and progesterone and their effect on the LES
Mechanical – the enlarging uterus increasing intra-abdominal pressure, inducing reflux of gastric acid
Behavioral – as with other instances of heartburn, behavioral modifications can exacerbate or alleviate symptoms

Unknown origin
Functional heartburn is heartburn of unknown cause. It is commonly associated with psychiatric conditions like depression, anxiety, and panic attacks. It is also seen with other functional gastrointestinal disorders like irritable bowel syndrome and is the primary cause of lack of improvement post treatment with proton pump inhibitors (PPIs). Despite this, PPIs are still the primary treatment with response rates in about 50% of people. The diagnosis is one of elimination, based upon the Rome III criteria. It was found to be present in 22.3% of Canadians in one survey. Diagnostic approach
Heartburn can be caused by several conditions and a preliminary diagnosis of GERD is based on additional signs and symptoms. The chest pain caused by GERD has a distinct burning sensation, occurs after eating or at night, and worsens when a person lies down or bends over. It also is common in pregnant women, and may be triggered by consuming food in large quantities, or specific foods containing certain spices, high fat content, or high acid content. In young persons (typically <40 years) who present with heartburn symptoms consistent with GERD (onset after eating, when laying down, when pregnant), a physician may begin a course of PPIs to assess clinical improvement before additional testing is undergone.