Conversely, doses of 5 and 10 mg of norethisterone, which are used in the treatment of gynecological disorders, are converted at rates of 0.7% and 1.0% and produce levels of EE that correspond to those produced by 30 and 60 μg dosages of EE, respectively. The levels of EE formed by 0.5 and 1 mg of norethisterone have been estimated based on higher dosages as corresponding to 2 and 10 μg dosages of EE, respectively. At high doses, norethisterone may increase the risk of venous thromboembolism due to metabolism into EE. Neurosteroid activity
Like progesterone and testosterone, norethisterone is metabolized into 3,5-tetrahydro metabolites. Whether these metabolites of norethisterone interact with the GABAA receptor similarly to the 3,5-tetrahydro metabolites of progesterone and testosterone like allopregnanolone and 3α-androstanediol, respectively, is a topic that does not appear to have been studied and hence requires clarification. Steroidogenesis inhibition
Norethisterone is a substrate for and is known to be an inhibitor of 5α-reductase, with 4.4% and 20.1% inhibition at 0.1 and 1 μM, respectively. However, therapeutic concentrations of norethisterone are in the low nanomolar range, so this action may not be clinically relevant at typical dosages.Norethisterone and its major active metabolite 5α-DHNET have been found to act as irreversible aromatase inhibitors (Ki = 1.7 μM and 9.0 μM, respectively). However, like the case of 5α-reductase, the concentrations required are probably too high to be clinically relevant at typical dosages.
Dysmelia (from the Greek dys (δυσ-), "bad" + mélos (μέλος), "limb" + English suffix -ia) is a congenital disorder of a limb resulting from a disturbance in embryonic development. Types
Dysmelia can refer to
missing (aplasia) limbs: amelia, oligodactyly, congenital amputation e.g. tibial or radial aplasia
malformation of limbs: shortening (micromelia, rhizomelia or mesomelia), ectrodactyly, phocomelia, meromelia, syndactyly, brachydactyly, club foot
too many limbs: polymelia, polydactyly, polysyndactyly
others: tetraamelia, hemimelia, symbrachydactyly

Occurrence rate
Birth defects involving limbs occur in 1 per 1000. Causes
Dysmelia can be caused by
Inheritance of abnormal genes, e.g. polydactyly, ectrodactyly or brachydactyly, symptoms of deformed limbs then often occur in combination with other symptoms (syndromes)
external causes during pregnancy (thus not inherited), e.g. via amniotic band syndrome
teratogenic drugs (e.g. thalidomide, which causes phocomelia) or environmental chemicals
ionizing radiation (nuclear weapons, radioiodine, radiation therapy)
infections
metabolic imbalance

Syndromes with dysmelia
References
External links
DysNet: An organisation for people affected by Dysmelia (congenital limb difference)
Reach: Association for Children with Upper Limb Deficiency)