HPL Full Form

The human form of placental lactogen (HPL), also known as human chorionic somatomammotropin (HCS), is a polypeptide placental hormone (chorionic somatomammotropin). It has a similar structure and function to human growth hormone. It alters the mother’s metabolic status during pregnancy to help the foetus get enough energy. Anti-insulin properties are found in HPL. During pregnancy, the syncytiotrophoblast secretes the hormone HPL. Genes on chromosome 17q22-24 encode HPL, just like human growth hormone. It was discovered in 1963.

Structure

HPL has a molecular mass of 22,125 and is made up of a single chain with 191 amino acid residues linked by two disulfide bridges and eight helices. X-ray diffraction was used to identify the crystal structure of HPL to a resolution of 2.0.

Levels

HPL is only present during pregnancy, with maternal serum levels rising in tandem with the foetus and placenta’s development. Maximum levels are often obtained in the short term, at 5–7 mg/L (5-7 micrograms/ml). Patients who have had many pregnancies have higher levels. HPL reaches the foetal circulation in small amounts. It has a 15-minute biological half-life.

Physiologic Functions

HPL has the following effects on the maternal organism’s metabolic system:

• Although HPL replicates the activity of prolactin in a bioassay, it is unknown whether HPL plays a function in human lactation.

Metabolic

• Increased maternal blood glucose levels due to increased maternal insulin sensitivity.
• Glucose consumption by the mother, which aids in embryonic nourishment (the mother responds by increasing beta cells). A rise in HPL is caused by chronic hypoglycemia.
• Lipolysis occurs when free fatty acids are released. Fasting and the release of HPL make free fatty acids available for the maternal organism to use as fuel, allowing the foetus to use substantially more glucose. Ketones generated from free fatty acids can also pass through the placenta and be utilised by the foetus.
• Even in the case of maternal malnutrition, these functions aid embryonic feeding.
• HPL is a strong prolactin receptor agonist and a modest growth hormone receptor agonist.

What Roles Does Human Placental Lactogen Play During Pregnancy?

Around the second week of pregnancy, the placenta begins to manufacture human placental lactogen. Human placental lactogen circulates throughout your body by the third to sixth week. A blood test can reveal it around week six.

Lactogen levels in the human placenta gradually increase throughout your pregnancy. If you’re pregnant twins or other multiples, your human placental lactogen levels are likely to be higher than if you’re carrying a single foetus.

Human placental lactogen serves several important roles throughout pregnancy:

Regulation of metabolism. Human placental lactogen aids in the regulation of metabolism, or the conversion of lipids and carbohydrates into energy. This aids in the more effective breakdown of fats in diets, allowing them to be utilised as energy. It also aids in the liberation of glucose (sugar) for the foetus.

Insulin sensitivity. Human placental lactogen also reduces your body’s sensitivity to the effects of insulin, a hormone that transports glucose from the bloodstream into cells. This also means that there is more glucose in your system to feed the foetus.

Although human placental lactogen influences breastfeeding, its exact role in stimulating milk glands in the breasts is uncertain, and it does not appear to be a substantial factor.

How are the Levels of Human Placental Lactogen Determined?

A human placental lactogen test is performed similarly to a blood test. A needle is used to extract a small sample of blood from a vein in your arm by your doctor. In most circumstances, there isn’t much you can do to prepare for the test.

This test may be ordered by your doctor for a variety of reasons, including:

• You had a strange ultrasound
• The amniotic fluid surrounding the foetus decreases
• Your doctor suspects that the placenta is malfunctioning
• You have a high blood pressure condition
• It’s possible that you’re having a miscarriage
• You have a chance of getting gestational diabetes

What Do the Results Mean?

A high amount of human placental lactogen in the results could indicate:

• diabetes
• Lung, liver, or white blood cell cancers

The presence of a low amount of human placental lactogen could indicate:

• preeclampsia
• insufficient placenta
• miscarriage
• Hydatidiform mole and choriocarcinoma (uterine tumours)

Conclusion

The placenta releases a hormone called human placental lactogen during pregnancy. The placenta is a uterine structure that supplies nourishment and oxygen to a developing foetus.

Human placental lactogen levels gradually rise as the foetus grows. Human placental lactogen levels decrease after pregnancy.

Lactogen levels in the human placenta gradually increase throughout your pregnancy. If you’re pregnant twins or other multiples, your human placental lactogen levels are likely to be higher than if you’re carrying a single foetus.