What is rickets? How does it occur? Which minerals are responsible?
Rickets can be described as mineralization (use of calcium and phosphor in formation of bone tissue) disorder in growing bone tissue (prior to closure of the epiphyseal plate). This condition mostly develops in first year of life characterized by quickest growth in babies. Long bones grow through “ossification (osteogenesis)” of growth plates in both ends of bones. Sufficient amount of calcium and phosphor and precipitation of these minerals into growth plates are required for this process. Vitamin D ensures that calcium is absorbed from the intestines to obtain calcium and phosphor required for the growth process; therefore, Vitamin D has a major role in development of bones. Therefore, Vitamin D deficiency is the most common cause of rickets. In addition, low dietary calcium intake also contributes to rickets. The rarer case of rickets secondary to phosphorus deficiency occurs due to overexcretion of phosphorus by kidneys secondary to genetic disorders.
How does vitamin D deficiency occur and what are indicators of the deficiency?
Vitamin D is synthesized by the thermal energy absorbed by skin from the sun rays, it becomes active afterwards following enzymatic process stages in liver and kidneys and reaches the intestines, which are the most critical point of effect. Our body is not dependant to foods regarding its Vitamin D needs. However, it may not, sometimes, be possible for the babies to be exposed to sun sufficiently. In such cases, all babies require 400 units of medical Vitamin D supplement per day, especially within the first year of life. Vitamin D level of our body is quantified with level of 25-OH Vitamin D in our blood. Serum 25-OH Vitamin D below 12 ng/ml in childhood is specified as deficiency. There is risk of rickets in these children in association with effects of other contributing factors. In childhood, values ranging from 12 to 20 ng/ml point to deficiency, while a value above 20 ng/ml is considered normal.
What are symptoms of rickets?
Symptoms of rickets vary depending on the age range. For example, while symptoms which involve bones are not observed in newborn infants and too small babies, infants may also be admitted with convulsion secondary to calcium deficiency. In general terms, most common symptoms are restlessness due to bone aches, respiratory system infections at frequent intervals, inability to bear load, delayed walking, sweating in head, inability to gain weight, delay in tooth eruption, large anterior fontanelle or delay in closure of anterior fontanelle, leg deformities and convulsions, which we mentioned above. While rickets was a common problem in our country 30-40 years ago, it occurs rarely today. This achievement is based on the program that ensures the infants are administered 400 units of vitamin D daily. On the other hand, Vitamin D deficiency in adults leads to osteomalacia, which is characterized with insufficient dietary calcium and phosphorus required for regeneration of the bone tissues. Generalized body aches are observed in these patients.
How is rickets treated?
Treatment of rickets should be oriented to the underlying cause. The most common type of rickets, which is secondary to Vitamin D deficiency, is treated with Vitamin D supplementation at appropriate dosage (2000 units per day for infants under 3 months of age, 2000 units per day for 3- to 12-month old babies, 3000-6000 units per day between 12 months to 12 years of age, 6000 units per day and 50,000 units for 90 days or once at 3- to 12-month intervals for children older than 12, 150,000 between the age of 12 months to 12 years, 300,000 units for individuals above 12 years of age) Oral calcium supplementation along with Vitamin D for 2 weeks is also required for children. Vitamin D supplementation at above mentioned doses require final diagnosis of rickets, measurement of Vitamin D level in blood along with extra tests, such as serum alkaline phosphatase and parathyroid hormone as well as wrist X-ray. In other words, it is not appropriate to plan the treatment and administer high doses of Vitamin D solely based on the vitamin D level in blood. Oral phosphorus supplementation along with active vitamin D supplements is necessary in rickets cases secondary to phosphorus deficiency.
When should Vitamin D supplement be started for children and how should the dose be determined?
We recommend 400 units of Vitamin D daily for all babies immediately after birth until they are 1 year old. Vitamin D is already provided free-of-charge for all infants in our country since the year 2005, within scope of “Ministry of Health Vitamin D Supplement Program”. Three drops of Vitamin D will be sufficient for this supplementation. Children require 600 units of vitamin D after the age of 1, but it is not necessary to meet all needs in the form of a pharmaceutical preparation. We usually recommend oral administration of Vitamin D until the age of 2. Afterwards, the children are able to synthesize Vitamin D sufficiently in their skin and store it for the winter as long as they are exposed to sun. Daily intake of Vitamin D at dose of 800 units per day becomes necessary after the age of 70. In most cases, healthy people can synthesize the required amount of Vitamin D in their skin, but there is no contraindication that prevents them from receiving daily Vitamin D at these amounts in the form of a pharmaceutical preparation. On the other hand, Vitamin D supplementation beyond this dose has no additional benefits regarding the human health.
What does overdose of Vitamin D supplementation causes?
Excessive vitamin D leads to elevation of calcium in blood followed by precipitation of excessive calcium to kidneys and formation of stones. Elevated calcium level in blood (hypercalcemia) also leads to lack of appetite, nausea, stomach ache, urinary frequency and polydipsia. When blood calcium is too high, altered mental status, a condition called encephalopathy, may occur. Too high vitamin D is caused by excessive Vitamin D supplementation despite absence of rickets or osteomalacia. Studies usually show that vitamin D reading equal to 16 to 20 ng/ml is sufficient; amounts that exceed this range demonstrate a flat line and elevating vitamin D levels above 20 ng/ml has no additional benefits and it is “possibly harmful” if above 50 ng/ml.
What are the mistakes regarding Vitamin D supplementation?
Most common mistake regarding Vitamin D supplementation is administering high doses (such as 1 vial of Vitamin D per week) to increase vitamin D level above 30 ng/ml. As we mentioned above, Vitamin D around 20 ng/ml is sufficient for humans and therefore, administration of Vitamin D above 400-600 units per day is unnecessary. Moreover, it is unnecessary to monitor Vitamin D in healthy children and adults.
Why did Vitamin D gain importance during Covid-19 pandemic?
The popularity of Vitamin D supplementation in Covid-19 pandemic is essentially caused by long-term discussions regarding positive effects of Vitamin D on the immune system and resultant positive effects on prevention of infections and recovery. The truth is we know that the evidence on this subject is insufficient and even weak, but this opinion gained fair popularity, similar to most opinions that “are not based on evidence”. In addition, one or two articles stating that high dose Vitamin D supplementation lowers deaths caused by Covid were published in some countries with Covid 19 epidemic and the subject became tangled when these articles were covered by the media to a large extent. These studies were small-scaled ones and double-blind control group was not used in these studies. Moreover, baseline vitamin D levels are not known in one study and the group that was not supplemented vitamin D included more severe cases. When the United Kingdom government brought Vitamin D support into agenda regarding Covid-19, opinions of many scientists who stated there was not sufficient evidence on this subject were overshadowed and vitamin D supplementation literally "exploded" around the world.
Contrarily, Israeli researchers reported that there is no increase in incidence of infections in individuals with Vitamin D receptor dysfunction, who were therefore expected to experience all problems caused by Vitamin D deficiency most severely. In conclusion, it will be beneficial to be careful on this subject until more comprehensive studies are published. On the other hand, Vitamin D supplementation at dose of 600 units per day, especially during winter, is also recommended and it causes no drawbacks. If there are any benefits to be gained from Vitamin D regarding Covid 19, we can state that daily Vitamin D intake of 600 units is sufficient for this purpose.
Prof. Şükrü Hatun, M.D.
School of Medicine, Koç University
Pediatric Endocrinology and Diabetes Division