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• Non-insulin-dependent diabetes(Type 2) (also calledadult-onset diabetesandmaturity-
  onset diabetes), is a complex progressive metabolic disorder characterised byb-cell failure
  and variable insulin resistance. A subtype ismaturity-onset diabetes of the young(MODY)
  which usually occurs before the age of 25 years. It is the first form of diabetes for which
  a genetic cause and molecular consequence have been established. Mutations of the genes
  for hepatocyte nuclear factor 4a(MODY1), glucokinase (MODY2), HNF1a(MODY3), insulin
  promotor factor 1 (MODY4), HNF1b(MODY5) and neurogenic differentiation factor 1
  (MODY6) have all been characterised.

Case study PREGNANCY

A 28-year-old female PE teacher presented to her GP with non-specific symptoms of increased

tiredness, nausea, stomach cramps and amenorrhoea with a last menstrual period 3 months

previously. She was a previously fit, healthy lady who had a normal menstrual history. Having recently

moved house, she thought that stress might be the cause of her symptoms. Her GP requested routine

biochemistry tests including thyroid function tests, all of which were within normal reference range.

A urine pregnancy test was also performed and to the patient’s surprise was positive and confirmed

by laboratory serumb-human chorionic gonadotropin (b-hCG) of 150 640 IU dm^3.

Comment These results confirm that this lady was approximately 10 weeks pregnant. The serumb-hCG levels
during pregnancy are shown in Fig. 16.5. A level>25 IU dm^3 is indicative of pregnancy. Implantation
of the developing embryo into the endometrial lining of the uterus results in the secretion ofb-hCG
and as pregnancy continues its synthesis increases at an exponential rate, doubling every 2 days, and
reaching a peak of 100 000–200 000 IU dm^3 at 60–90 days (1st trimester). Levels then decline to
approximately 1000 IU dm^3 at around 20 weeks pregnancy (during 2nd trimester) to a stable plateau
for the remainder of the pregnancy. Oestradiol, oestrone, oestriol and progesterone all increase in
the early stages of pregnancy as a result of the action ofb-hCG on the corpus luteum of the ovaries.
Unlikeb-hCG levels, the levels of the three oestrogens and progesterone continue to rise during
pregnancy playing a vital role in the sustenance and maintenance of the foetus. At the end of
pregnancy, the placental production of progesterone falls, stimulating contractions leading to birth.

Weeks

% Highest mean

plasma level

0

0

10 20 30 40

Luteo-placental shift

50

100

Ovulation

Conception

Human chorionic

gonadotropin (hCG)

Placenta

Progesterone

Total oestrogen

Placental lactogen

Birth

Fig. 16.5Hormonal profile during pregnancy. (Adapted with permission from Professor Alan S. McNeilly,

MRC Human Reproductive Science Unit, Edinburgh, UK.)

653 16.3 Examples of biochemical aids to clinical diagnosis