We read with interest the recent article in Indian Pediatrics by Shah, et al. [1], and have the following comments to offer:

Though the authors have excluded patients with known parathyroid disease, rickets, renal tubular acidosis, chronic kidney disease or a diagnosis of acute kidney injury at admission, about 56% children were stated to have some underlying chronic illness. One would be really interested to know the nature of these chronic illnesses, as many diseases such as chronic liver disease [2] and nephrotic syndrome [3] are known to have low vitamin D levels. The authors have also not mentioned whether any of these children with chronic diseases were on long-term medications known to affect vitamin D-calcium-parathyroid axis such as Cortisteroids for nephrotic syndrome, Rifampicin for tuberculosis, and antiepileptics for epilepsy [4]. Authors stated that 15 patients were admitted with liver disease and 24 with neurological diseases; the disease condition and/or the medication used in these children can lead to a decrease in vitamin D and calcium levels.

In this study, ‘parathyroid-responder’ was defined as children with serum parathyroid hormone (PTH) >65 ng/mL with 25(OH)D <20 ng/mL, and/or calcium corrected for albumin <8.5 mg/dL. But it is not clear why the authors chose to analyze children with hyperparathyroidism secondary to 25(OH)D deficiency alone, and leave out non-vitamin D-deficient children with hypocalcemia-related hyperparathyroidism.

It would have been useful to evaluate the ionized calcium (iCa) levels of these critically-ill children in addition to the total calcium adjusted for albumin. Though iCa levels are nor reported, in view of very high incidence (59%) of hypocalcemia in the study population, one would be really inquisitive in knowing whether calcium supplemention was given to the hypocalcemic children, especially to those with septic shock.

The authors mention that data regarding type of milk-product consumption by the children was recorded but the same has not been presented in the results.

1. Shah SK, Kabra SK, Gupta N, Pai G, Lodha R. Vitamin D deficiency and parathyroid response in critically-ill children: Association with illness severity and clinical outcomes. Indian Pediatr. 2016;53:479-84.

2. Iruzubieta P, Terán Á, Crespo J, Fábrega E. Vitamin D deficiency in chronic liver disease. World J Hepatol. 2014;6:901-15.

3. Freundlich M, Bourgoignie JJ, Zilleruelo G, Abitbol C, Canterbury JM, Strauss J. Calcium and vitamin D metabolism in children with nephrotic syndrome. J Pediatr. 1986;108:383-7.