Difference Between Achondroplasia and Pituitary Dwarfism

Dwarfism: Diagnosis, Imaging & Hormonal Testing for Short Stature Conditions

Pituitary dwarfism and achondroplastic dwarfism are distinct conditions which cause short stature in individuals. However, they differ in their underlying causes and how they affect growth. Here we will discuss some key comparisons between these two and new treatments to treat dwarfism.  

Key Differences Between Pituitary Dwarfism and Achondroplastic Dwarfism

Here in this table, we will discuss the key differences between pituitary and achondroplastic dwarfism.

How to Diagnose Dwarfism?

Various diagnostic tests are available to diagnose dwarfism, including imaging studies and physical examinations. Some doctors may use prenatal ultrasound to detect dwarfism before birth but may start the diagnosis process after delivery.

Let us explore these tests in detail:

• Physical Measurements: Doctors primarily run a normal physical examination of the weight, height, and head circumference of that particular individual. They will take a chart to observe the recurrent percentile ranking for each of these parameters. This is integral for doctors to identify any abnormalities, like delayed growth or a disproportionately large head.
• Appearance: Specific facial and skeletal features play a crucial role in diagnosing dwarfism. Different facial and skeletal traits can help doctors differentiate various types of dwarfism, guiding them towards specific diagnostic tests and genetic analysis. In adults, a height of 4 feet 10 inches (147 cm) or less is one criterion for a diagnosis of dwarfism. In children, diagnosis focuses on a growth rate that is significantly slower than expected for their age and sex, causing them to fall well below standard growth percentiles.
• Imaging Technology: Modern imaging techniques, such as ultrasound, X-rays, CT scans, PET and MRI, can diagnose dwarfism both in children and adults. Dwarfism may exhibit abnormalities of the skull and skeleton. An X-ray may reveal delayed bone development, which is a key indicator of growth hormone deficiency.
• Genetic Tests: Genetic tests can detect causal genes like the FGFR3 gene of dwarfism and other underlying issues. However, these tests do not necessarily make an accurate diagnosis regarding the genotypic trait of dwarfism. Chromosomal assessment is a good alternative to detect any kind of addition or deletion in chromosomes, which can lead to dwarfism.
• Family History: Sometimes doctors may check the stature of all your family members to determine the prevalence of dwarfism. If all of your family members are of short height, there is a high chance that dwarfism is prevalent in your lineage. However, if everyone has normal height, you may have some genetic discrepancies.
• Hormone Tests: For suspected Growth Hormone Deficiency, hormone stimulation tests are crucial to confirm low GH secretion. For disproportionate dwarfism like achondroplasia, diagnosis is based on physical features, radiographs, and genetic testing, as hormone levels are normal. These tests help determine if the pituitary gland is producing enough GH, which is essential for normal growth and development. Apart from these, there are other diagnostic tests to assess the levels of thyroid hormones or IGF-1 (Insulin-like Growth Factor-1) to detect dwarfism.

What is the New Treatment for Dwarfism?

Treatment of dwarfism depends on the underlying cause and type of dwarfism. For growth hormone deficiency, doctors prescribe hormone therapy. However, for conditions like achondroplasia, treatment focuses on managing complications and improving the quality of life.

Recently, many doctors have prescribed Voxzogo to children who are suffering from achondroplasia. It is a common drug to address the delayed bone maturation over the entire body during the adolescent phase.

How Does Voxzogo Work?

The FGFR3 gene in patients with achondroplasia is permanently active, preventing normal bone maturation and the formation of shorter bones. Vosoritide, the active substance in this medicine, binds to a receptor known as natriuretic peptide receptor type B (NPR-B). This reduces the activity of the FGFR3 gene, eventually stimulating bone growth and maturation.

In clinical trials, children taking Voxzogo showed an increase in annual growth velocity of approximately 1.5 to 1.6 cm per year compared to those receiving a placebo.

Achondroplasia is an autosomal dominant condition, which means a single copy of the gene from either parent is enough to develop this disease. On the other hand, pituitary dwarfism occurs due to a genetic mutation or deficiency in growth hormone. Consult with a healthcare provider to get proper guidance regarding the causes and underlying issues.

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