Topic Vitamin D is in vogue these days in research as well as clinical practice. The topic of the paper is interesting and very relevant. Introduction The roles of vitamin D in low back pain, or muscular function have not been indicated in the introduction. No published studies on Vitamin D and backache have been mentioned. Material and Methods The section has been written in paragraphs without any breakup into subheads. Patients: The study examines data from 200 patients and 200 controls. Exclusion criteria do not include rheumatoid disease which is a common, important and entirely a different entity. Tests: Methods used for estimation of the parameters not mentioned. The study does not even explain the method used for Vitamin D estimation. There is considerable variation from method to method in Vitamin D levels. Division of patients into four age groups is not justified. What determined this division is not clear. Results Poorly planned and written. Table 1: * Why not compare the demography of cases with controls rather than showing only cases. * 'Vit D' levels are shown in table 1 ……. Is it 25(OH) Vit D? If yes, the value differs in table 3. * 'Fasting plasma lucose[mg/dl]' - do the author mean glucose? * 'Total count' - of what? Is it Total Leukocyte count? Table 3: * The standard deviation values are inconsistent - the number of decimal point varies from 2 to 4? * Values of CRP and RA Factor unrealistically high for patients with no complaint other than backache. Table 4: Not required. Only variance of Vitamin D with age could have been given in the text. Fig 1 & 2 show only well-established facts. If there was any difference in this relationship in the control group, has not been given. Fig 3. Not required. Discussion Very poorly written and out of context at many places. P5, L30-35: Reference is missing. P5, L38: "Serum 25 (OH) D is a potent indicator of total body vitamin D because there is no other biomarker …." - The statement that 25 (OH) D is a potent indicator of Vit D because "there is no other biomarker" is preposterous. How can a marker be an indicator just beco's there is no alternative? P5, L55: "VDR" ? P5, L55: "Higher 25(OH)D concentration>16 ng/ml" - if 16 ng/ml is the limit then how Vitamin D insufficiency is defined as levels <30 ng/ml (P6, L4). P6, L35&L37: "10 mg/ml" ….. "30 mg/ml"? 25(OH)Vit D is reported in ng/ml in rest of the paper. P6, L52: "HOMAIR"? What is HOMAIR? P6, L52: "They concluded" - Who is 'They'?

There is no discussion on CRP or Rheumatoid factor. Are these two biomarkers involved in back pain? or the patients had some other underlying disease causing elevated levels of CRP and RA factor. In fact authors have estimated 11 laboratory parameters but have not discussed any of them except Vit D in the discussion section. If they were not important, they should not be included in the paper.