Rickets: Symptoms and Signs of Vitamin D Deficiency

Rickets in children is a disorder of the mineralization of growing bone tissue, causing bones to become soft and deformed, affecting growth, posture, and motor skills. The most common cause is vitamin D and calcium deficiency due to an unbalanced diet, low sun exposure, or a combination of these factors. Rarely, genetic forms are found that impair phosphate metabolism and the activity of enzymes responsible for vitamin D metabolism. The clinical picture consists of bone deformities, muscle weakness, and systemic manifestations, depending on age and the severity of the deficiency.

Even the initial symptoms interfere with a child's normal growth and development, so early recognition of symptoms is key to preventing irreversible deformities. In infants, signs may be unnoticeable to parents, but are easily detected with a targeted examination. As children begin to walk, symptoms become more obvious: the shape of the legs changes, a "bracelet-like" thickening appears at the wrists, and "rosary beads" appear along the ribs. The earlier diagnosis and treatment are initiated, the higher the chance of full bone restoration.

Modern observations show that rickets remains a common problem even in developed countries, especially in children with dark skin, limited sun exposure, premature babies, and breastfed infants without vitamin D supplementation. In countries with low calcium intake, a calcium-deficient variant is common, which exacerbates deformities with normal exercise. Therefore, it is important to evaluate symptoms in the context of diet, climate, cultural habits, and underlying medical conditions.

In recent years, updated guidelines for the prevention and early recognition of rickets have been published. They emphasize the need for routine risk and symptom assessment during preventive visits, including musculoskeletal examinations, posture, and gait assessments. This approach allows for the selection of children for laboratory testing and imaging without overburdening the healthcare system.

How symptoms develop: what happens to the bone

In children, the metaphyses of long bones—the active growth zones—must be mineralized with calcium and phosphate in a timely manner, under the control of vitamin D. When there is a deficiency, mineralization is delayed, and the flexible organic bone matrix does not have time to strengthen, causing the metaphyses to become widened and loosened. This causes characteristic clinical and radiographic signs: a funnel-shaped "cup" and "fringed" appearance of the metaphyseal margins, thickening, and tenderness in the growth zones. Against this background, any load leads to progressive deformities.

Mineral deficiency affects more than just bones. Muscle tone decreases, proximal myopathy develops, and the child is slower to hold up his head, sit up, and walk. In severe cases, hypocalcemia causes seizures and cardiac dysfunction in infants. Combined with growth retardation, this creates an "integrated" symptom complex that the doctor should recognize during the first visit.

It's important to remember two main pathobiological trajectories. In vitamin D deficiency, signs of calcium malabsorption and secondary hyperparathyroidism predominate; in phosphate deficiency states, such as hereditary hypophosphatemia, chronic renal phosphate loss becomes the dominant pathology, causing symptoms to be more pronounced in the lower extremities and spine, and muscle weakness and pain often worsening. The clinical phenotype guides the physician toward the appropriate examination algorithm.

With increasing load at the onset of walking, deformities progress rapidly: the soft bones of the lower leg bend outward or inward, a "duck" gait develops with pelvic instability, and kyphosis or kyphoscoliosis worsens. Without treatment, these changes become permanent and require complex orthopedic correction later. Therefore, any deviations in gait and leg shape in young children are a reason for examination.

Early symptoms in infants

In infants, mild symptoms predominate during the first months: increased scalp sweating, restless sleep, irritability, and frequent awakenings. These symptoms are nonspecific, but when combined with a vitamin D deficiency, they require an examination of bones and muscle tone. In the early stages, "craniotabes" is detected—softening of the occipital and parietal bones, with fingers "pressing" into the bone like a box lid.

Then, thickening of the ribs appears where they connect to the cartilage, forming a "rachitic bead" that is easily palpated along the anterior surface of the chest. Another characteristic sign is a delayed closure of the anterior fontanelle and a prominent forehead, giving the head a "square" appearance. With severe deficiency, seizures are possible due to low calcium levels, especially in breastfed infants without vitamin D supplementation.

Muscle weakness manifests itself as lethargy in the child: they are slow to hold their head up, roll over, and sit up. When attempting to stand the child up, they exhibit unsteady balance and tremors. These signs reflect not only the condition of the bones but also inadequate muscle function due to calcium and phosphate deficiency.

An early dental marker is delayed tooth eruption and decreased enamel quality, leading to a risk of future caries. Confirming the diagnosis at this stage allows for treatment with vitamin D supplements and nutritional adjustments, without requiring lengthy orthopedic rehabilitation.

Classic bone signs in toddlers and preschoolers

When a child begins to walk, the load on the shins and knees increases dramatically, and the "soft" bones become deformed. Bowed or "X"-shaped curvatures of the legs appear, along with thickening and tenderness in the wrists and shins. A "rachitic bead" is visible on the ribs, and "bracelet" appearance appears at the wrists and ankles due to widening of the metaphyses. Parents often complain of "clumsiness" and fatigue when walking.

The rib cage changes shape, developing a "chicken chest" or flattening of the sides with Harrison's fissure, where the diaphragm "presses" the soft rib cage inward. The spine responds by increasing thoracic kyphosis or developing scoliosis. These deformities progress with calcium and phosphate deficiency, so timely treatment prevents the malformation from becoming permanent.

Growth slows, the rate of body length gain decreases, and a disproportionate appearance appears: a relatively long torso against a background of shortened legs. Upon examination, changes in gait and support are noticeable: the child places their legs wide apart and "rolls" from one foot to the other to reduce pain and stress on the knees. These are functional cues the doctor may suggest for a targeted examination.

In severe cases, bone and muscle pain increases, nighttime awakenings occur, and active play is avoided. Without treatment, persistent axial deformities develop, requiring orthopedic braces or later surgical correction. Therefore, any child with progressive bowed legs should be examined for rickets.

Muscular, neurological and systemic manifestations

Proximal muscle weakness is one of the earliest and most persistent symptoms. The child has difficulty rising from a chair, getting off the floor without support, running, and jumping. A positive Gower sign, where the child "pulls" themselves up their legs with their hands when standing, reflects weakness of the hip and gluteal muscles. Improvement occurs as the deficit is corrected and the muscles strengthen.

Hypocalcemia can manifest as seizures in infants and paresthesias and carpopedal spasms in older children. In rare cases, infants develop cardiac manifestations, including cardiomyopathy, highlighting the need for immediate calcium and vitamin D supplementation. Such episodes require urgent hospitalization.

Dental problems are characterized by delayed eruption, enamel defects, and a high susceptibility to caries. In phosphate-deficiency forms, dental problems are more severe, and children are more likely to develop dental abscesses without an obvious cause. A dental examination by a dentist experienced in pediatric endocrinology helps ensure early detection.

Systemic complaints include fatigue, irritability, decreased physical endurance, and decreased interest in active play. These are nonspecific symptoms, but when combined with skeletal and muscular symptoms, they increase the likelihood of diagnosis and require laboratory confirmation.

Age specificity of symptoms

In newborns and infants in the first months, soft cranial signs and seizures are the most common symptoms associated with severe calcium deficiency. Feeding difficulties, lethargy, scalp sweating, and delayed motor milestones are also present. At this stage, the clinician relies on palpation of the sutures, fontanelles, and ribs.

In children aged 6 to 18 months, "classic" bone signs predominate: "rickets," "bracelet" deformities at the wrist and ankle, and thickening of the metaphyses of the long bones. Delays in standing and walking skills, uncertain support, and decreased endurance appear. This is a window of opportunity for rapid treatment and prevention of deformities.

Preschoolers and younger schoolchildren who actively walk and run have more pronounced axial leg deformities, gait and posture disturbances, and leg pain after exercise. In phosphate-deficiency forms, the changes are resistant to standard doses of vitamin D, suggesting a different diagnosis to the doctor.

Rickets is less common in adolescence but can present with bone pain, muscle weakness, short stature, and residual deformities. Chronic bowel or kidney disease, or genetic hypophosphatemia, require a different approach and active screening for symptoms.

Table 1. Age and most typical symptoms

Age	Typical manifestations	What to look for during inspection
0-6 months	Craniotabes, protruding forehead, convulsions in severe deficiency	Palpation of the skull and ribs, neurological status
6-18 months	"Rachitis beads", "bracelets" on the wrists, delayed walking	Gait, leg shape, growth zones
2-6 years	Bowed legs, chicken breasts, fatigue	Posture, distance between knees and ankles
7-12 years old	Leg pain, progressive deformities, short stature	Orthopedic angles and segment lengths

How to distinguish forms by symptoms

Vitamin D deficiency causes diffuse bone softening, classic signs in the wrists and ribs, muscle weakness, and skill delays. Rapid improvement occurs after initial vitamin D and calcium supplementation. If symptoms persist, alternative causes are sought.

In phosphate deficiency forms, including hereditary hypophosphatemia, the clinical presentation is dominated by underlying pain, leg deformities, and short stature, with a relatively less pronounced "rickets." Dental abscesses and early enamel damage are frequently observed. Standard doses of vitamin D are weakly effective, and the profile dictates the need for specific therapy.

In children with chronic kidney disease, rickets symptoms are combined with signs of mineral-bone dysfunction: growth retardation, pain, deformities, and muscle weakness. In this case, vitamin D deficiency and secondary hyperparathyroidism are combined with phosphate imbalance, so clinical management and symptom interpretation require the involvement of a nephrologist.

If a child has significant deformities but no significant risk factors for vitamin D deficiency, genetic variants should be considered. A family history of short stature, early orthopedic surgery in relatives, and dental problems increase suspicion.

Table 2. Symptom clues for probable types of rickets

Clinical signs	More for vitamin D deficiency	More for phosphate-deficient forms
"Rachic rosary", "bracelets"	Often expressed	Less pronounced
Dental abscesses, enamel defects	Rarely	Often
Response to standard doses of vitamin D	Good	Insufficient
Short stature for school age	Moderate	Expressed

Red Flags: When Urgent Help Is Needed

Convulsions, severe muscle weakness with respiratory distress, and signs of heart failure in infants are reasons for immediate hospitalization and urgent calcium correction. Delayed detection can lead to serious complications.

Rapidly progressing leg curvature, severe pain, and an inability to walk the usual distance for one's age are indications for an urgent consultation with a pediatric orthopedist and endocrinologist. This requires rapid imaging and initiation of therapy.

If hereditary forms of hypophosphatemia are suspected, referral to a specialized center is required for confirmation of the diagnosis and selection of targeted therapy. Timely diagnosis determines the growth prognosis and the need for future surgeries.

Children with chronic kidney disease and severe bone symptoms require joint care by a nephrologist and endocrinologist. Clinical progression may be faster than with classic vitamin D deficiency.

Table 3. "Red flags" in symptoms

Symptom	What does it mean?	Action
Convulsions in a baby	Severe hypocalcemia	Urgent hospitalization and calcium correction
Rapid growth of deformations	Active rickets, high risk of fixation	Accelerated imaging and therapy initiation
Difficulty walking, severe pain	Bone weakness, risk of fractures	Urgent consultation with an orthopedist
Short stature with dental abscesses	Possible hypophosphatemia	Referral to a specialized center

Diagnostic guidelines based on symptoms

The clinical assessment begins with an examination of the head, chest, spine, arms, and legs, and an assessment of gait and fatigue. Palpation of the metaphyses of the wrists and ankles helps identify "bracelet" joints, inspection of the ribs reveals "rickets," and measuring the distances between the knees and ankles quantifies axial deviations. These simple steps allow one to suspect the diagnosis even before the laboratory examination.

X-rays of the wrist and knee confirm the active process: cupping and fringing of the metaphyses, widening of the growth plate, and bone loss. In the early stages of infants, X-rays may be insensitive, and clinical signs take precedence, further emphasizing the importance of a thorough examination.

Laboratory markers help explain the symptoms: vitamin D deficiency often results in low calcium and phosphorus levels, elevated alkaline phosphatase, and elevated parathyroid hormone; phosphate-deficiency forms of the disease typically have persistently low phosphorus levels with normal or moderately low calcium and elevated alkaline phosphatase. The combination of symptoms and profile guides treatment.

In cases of risk of severe complications, children are observed inpatient until symptoms stabilize and treatment begins. Nutrition, vitamin D supplementation, and a follow-up plan are discussed.

Table 4. Symptoms and expected laboratory profiles

Clinical picture	Calcium	Phosphorus	Alkaline phosphatase	Parathyroid hormone	Suspicion
Classic bone signs, marked muscle weakness	Short	Low or normal	High	High	Vitamin D deficiency
Persistent leg deformities, dental abscesses	Normal or slightly reduced	Short	High	Normal or moderately elevated	Phosphate deficiency forms
Severe symptoms in chronic kidney disease	Low or normal	Tall or normal	High	High	Mineral-bone disorder in kidney disease

Common recognition errors

Some symptoms are attributed to "individual characteristics": parents believe that "all children get tired" or "their legs will straighten out on their own." However, with rickets, if left untreated, deformities become permanent, and muscle weakness delays development. It's important to explain to families that early correction prevents surgeries and lengthy rehabilitation.

Sometimes, a dentist notices the first signs due to delayed eruption and enamel defects. This isn't a localized problem, but a systemic signal of mineral deficiency. Communication between the pediatrician and dentist expedites diagnosis and treatment.

Another mistake is relying solely on vitamin D when hereditary hypophosphatemia is suspected. If symptoms and deformities persist, the child should be referred to a center where targeted therapy is available, which fundamentally changes the prognosis.

Finally, underreporting symptoms in children with chronic kidney disease leads to delayed initiation of comprehensive treatment. This requires a collaborative management protocol with a nephrologist and regular assessment of symptoms and growth.

Table 5. What can “mask” rickets?

Delusion	Why is this a mistake?	What to do
"The legs will straighten themselves"	In active rickets, deformations are recorded	Assess the axis, take an x-ray, and begin therapy.
"It's just late teething."	Enamel defects and abscesses indicate mineral deficiency	Refer to a pediatrician and endocrinologist
"Enough vitamin D for everyone"	Targeted therapy is needed for hypophosphatemia	Check phosphorus and direct to center
"Fatigue due to character"	Proximal weakness is a symptom	Show the exercises and start correction

How symptoms change during treatment

Within 2-4 weeks of vitamin D and calcium supplementation, pain and muscle weakness subside, the child becomes more active, and sleeps better. During examination, tenderness and thickening of the metaphyses subside, and the appearance of the "bracelets" diminishes. These are the first clinical signs of the correct approach.

After 3-6 months, gait and endurance improve, and angular deformities of the legs decrease if treatment is started early. If treatment is started late, persistent axial deviations require orthopedic splints and rehabilitation, and sometimes surgery in older patients. The clinician monitors progress using standard angles and distances.

In hereditary hypophosphatemic variants, early initiation of targeted therapy reduces pain, accelerates metaphyseal healing, and improves quality of life. Parents note that their child can play longer without fatigue and has fewer leg complaints. This is a direct result of normalizing blood phosphate levels.

In children with chronic kidney disease, symptom progression depends on monitoring phosphorus, parathyroid hormone, and vitamin D levels. Improvement is manifested by reduced pain, increased activity, and growth stabilization. Management is carried out using specialized protocols.

Table 6. Expected dynamics of symptoms with the correct tactics

Time after the start of treatment	What the family sees	What does the doctor record?
2-4 weeks	Less pain, better sleep, more activity	Reducing pain in the metaphyses
3-6 months	Improved gait, less fatigue	Reduction of deformation angles, normalization of laboratory parameters
6-12 months	Catch-up growth, persistent endurance	Disappearance of active X-ray signs
More than 12 months	Stable function and age-appropriate sports	Supportive observation