Failure to thrive/slowed growth
Children with cystinosis may have normal weight and height at birth, but their growth does not keep up with expectations. This is called “failure to thrive” or “slowed growth” and can be an early indicator of cystinosis, usually becoming evident at 6 to 12 months of age.1
- Feeding difficulties such as feeling full from consuming large amounts of fluids, lack of appetite (anorexia), vomiting, lacking saliva, and a distorted sense of taste, combined with losses of nutrients in the kidneys, can result in poor nutrition and contribute to slowed growth.1,2 See the Nutrition page to learn more.
- Underperformance of the thyroid, called hypothyroidism, can also contribute to slowed growth.3
- Poor growth is also partially due to metabolic acidosis, or the buildup of acid in the body.2
Cystinosis is the most common cause of Fanconi syndrome, a disorder of the kidney tubules that typically appears in cystinosis patients at around 6 months of age.1 Fanconi syndrome occurs when the renal tubules—tiny canals in the kidneys responsible for reabsorption, secretion, and collection of various substances—cease to function properly. Fanconi syndrome causes loss of many key substances necessary for normal health, including glucose, phosphate, amino acids, calcium, magnesium, sodium, and potassium.2 Urination increases dramatically in Fanconi syndrome, resulting in dangerous dehydration, which worsens kidney impairment and requires immediate medical attention.1
In people with cystinosis, important minerals can be lost because of frequent urination. One important nutrient that can be lost is phosphorous. A person who loses too much phosphorous can develop rickets, a softening or weakening of bones.1,4 Although a deficiency of vitamin D is typically the cause of rickets, when rickets occurs in people with cystinosis, it is generally hypophosphatemic rickets, rickets caused by too little phosphorus.2,4 In addition to bone softening, rickets can cause bone deformities and bone fragility, and delay walking in young children.1