Tetany in neonates is a medical condition characterised by intermittent muscle spasms, tremors or convulsions caused by an imbalance in calcium or other minerals in the body.¹ While it is rare and uncommon, it is a significant issue that requires timely recognition and management to prevent serious complications. In this article, we will discuss briefly the causes, symptoms, diagnosis and treatment approach for tetany in neonates, providing a comprehensive overview of this condition.

What is tetany?

Tetany refers to a condition of increased neuromuscular excitability, leading to involuntary muscle contractions. It commonly manifests as cramps, spasms, or even seizures. In neonates, tetany can occur due to disruptions in the delicate balance of electrolytes, particularly calcium, magnesium, and phosphate. Tetany may occur at any time during the newborn period. It is seen in full-term as well as premature infants and affects both males and females in equal numbers. It can cause:

• Tingling or numbness (  especially in the hands, feet and  face)
• Muscle cramps or spasms 
• Signs like  Chvostek’s signs (facial twitching when tapping the cheeks) or Trousseau’s sign (hand spasms when a blood pressure cuff is inflated).

Severe cases may involve breathing difficulties like throat spasm, which can be life-threatening. This happens because low calcium disrupts nerve function, making them hyperactive. Severe hypocalcemia, especially when calcium levels drop below 7 mg/dL, significantly raises the risk of tetany.^2,3 

Understanding Neonatal Tetany 

Neonatal tetany usually presents within the first few weeks of life, especially in babies who were at high risk because they were born with a low birth weight. growth retardation, moms with diabetes, maternal PHP, and long, hard deliveries.⁴ 

It can be short-term or indicative of an underlying metabolic or physiological issue. The most common cause is hypocalcemia (low levels of calcium in the blood), but other imbalances like hypomagnesemia and hyperphosphatemia can also trigger it.

Cause of Tetany  in Neonates

Several factors can contribute to tetany in neonates, including both transient and persistent causes. Understanding these causes is crucial for effective treatment.

Hypocalcemia

Hypocalcemia is the leading cause of tetany in neonates and can be categorised into early-onset (within 72 hours of birth) and late-onset hypocalcemia.⁵ 

1. Early-onset Hypocalcemia: This type typically occurs in premature infants or those with perinatal complications. Factors include:

• Prematurity: Preterm infants often have underdeveloped parathyroid glands and low calcium reserves.
• Birth asphyxia: Oxygen deprivation during birth can impair calcium metabolism.
• Maternal diabetes: Infants of diabetic mothers are at increased risk due to suppressed parathyroid hormone (PTH) secretion.

2. Late-Onset Hypocalcemia: This occurs after 72 hours of life and is often associated with:

• High phosphate intake (e.g., from formula feeding)
• Hypoparathyroidism: Reduced or absent PTH impairs calcium regulation
• Vitamin D deficiency: Essential for calcium absorption
• Late neonatal hypocalcemia (LNH), which is defined as hypocalcemia observed after postnatal 72 hours, is very unusual and generally related to increased phosphate load, hypomagnesemia, vitamin D deficiency, PTH resistance, primary hypoparathyroidism, maternal hyperparathyroidism, and metabolic syndromes (Kenny-Caffey syndrome, long-chain fatty acyl CoA dehydrogenase deficiency, Kearns-Sayre syndrome), or it is iatrogenic^4,6 

Hypomagnesemia

Magnesium plays a vital role in calcium homeostasis. Low magnesium levels can impair PTH secretion and function, leading to hypocalcemia and tetany. Neonatal hypomagnesemia is often secondary to maternal magnesium deficiency or gestational diabetes.⁷ 

Hyperphosphatemia

Elevated phosphate levels can bind to calcium in the blood, reducing ionised calcium levels and triggering tetany. This is commonly seen in neonates fed with formulas containing high phosphate concentrations.⁸ 

Vitamin D Deficiency

Vitamin D is critical for calcium absorption in the intestines. Deficiency in either the neonate or the mother can result in hypocalcemia and tetany. Conditions like maternal vitamin D deficiency during pregnancy or exclusive breastfeeding without supplementation are common risk factors.⁹ 

Symptoms of Neonatal Tetany

The clinical presentation of tetany in neonates can vary, but common symptoms include:

Neuromuscular Signs:

• Muscle spasms or cramps
• Twitching or tremors
• Clonus (rhythmic contractions)
• Carpopedal spasm (involuntary contractions of hands and feet)

Seizures: Generalised or focal seizures may occur in severe cases.

Neonatal hypocalcemia can cause symptoms like low muscle tone, poor feeding, stridor, jitteriness, and seizures, with seizures being the most serious. In newborns, seizures appear differently from older children due to immature brain activity.

Respiratory Symptoms: Apnea or difficulty breathing due to laryngospasm.

Behavioural Signs:

• Irritability or excessive crying
• Feeding difficulties

The signs of tetany in newborns are not specific. It should be considered if the baby shows convulsions, twitching, or unusual sensitivity.³ 

Treatment Approach 

Effective management of neonatal tetany requires addressing the underlying cause while stabilising the infant’s condition.

1. Immediate stabilisation:

• Seizure management- Intravenous (IV) anticonvulsants such as phenobarbital may be used to control seizures.¹⁰ 
• Calcium Supplementation- When newborns experience symptoms like tetany or convulsions due to hypocalcemia, a slow infusion of 10 to 20 mg/kg of elemental calcium (1–2 ml/kg/dose of 10% calcium gluconate) over 10 minutes under cardiac monitoring is recommended. This treatment helps prevent severe symptoms but does not normalise calcium levels. After the initial bolus, a continuous infusion of 50 to 75 mg/kg/day or 1 to 3 mg/kg/hour of elemental calcium should be started. After the initial dose, a continuous calcium infusion is preferred over intermittent doses every 6 hours. Calcium levels should be monitored every 8 to 12 hours and adjusted accordingly. Care must be taken to avoid tissue damage from the infusion, and the rate should not exceed 1 mg/min. Slow administration with cardiac monitoring is essential to prevent heart issues. If using an umbilical venous catheter, ensure it's correctly placed to avoid liver damage.¹¹ 
• Magnesium correction- Hypomagnesemia should be corrected with  IV magnesium sulphate if present.¹² 

2. Addressing the underlying cause

Tetany is typically diagnosed by detecting low calcium levels in the blood. They may also check the levels of parathyroid hormone (PTH), vitamin D, magnesium, and phosphorus to help determine the underlying cause of the condition. It's crucial to check magnesium levels during calcium repletion, as magnesium deficiency often causes treatment-resistant hypocalcemia. For mild hypocalcemia, oral calcium supplements, vitamin D, or magnesium tablets may be needed to restore calcium levels. After resolving the acute episode, future management should focus on addressing the underlying cause of tetany.¹³ 

3. Supportive Care

• Monitoring electrolyte  levels to guide  therapy
• Ensuring adequate hydration to maintain renal function 
• Regular  follow-ups  to assess growth and  development 

Conclusion 

Tetany in neonates, though rare, is a critical condition requiring timely diagnosis and treatment to prevent severe complications. It arises primarily from electrolyte imbalances, especially hypocalcemia, hypomagnesemia or hyperphosphatemia, and is often seen in infants with underlying health issues such as low birth weight, maternal diabetes, or difficult deliveries. Neonatal hypocalcemia, the most common cause, can present as early-onset or late-onset hypocalcemia, with late-onset cases often tied to metabolic syndromes or high phosphate intake.

Symptoms of tetany include muscle spasms, twitching, seizures, and potentially life-threatening respiratory issues such as laryngospasm. The most alarming manifestation is seizures, which appear differently in neonates compared to older children due to their immature neurological systems.

Treatment focuses on immediate stabilisation, including calcium supplementation, correction of magnesium deficiencies, and, if necessary, anticonvulsants for seizure control. Continuous calcium infusions under cardiac monitoring help manage acute symptoms, followed by oral supplements and vitamin D to maintain calcium levels. Addressing the root cause is essential for long-term management, whether the issue is related to maternal health, nutritional deficiencies, or congenital conditions. With proper treatment and supportive care, including monitoring electrolyte levels and ensuring hydration, the prognosis for neonatal tetany is generally favourable. Awareness among healthcare providers and parents is vital for recognising symptoms early and ensuring timely intervention.