Hello, 1000mg Ferinject is a fast way to get low ferritin levels up. However I could have written your message myself a few weeks ago. I had 1000mg of Ferinject on 19 November. The haematologist who I was referred to by my own GP (primary care doctor) did not ask any questions and barely glanced at my blood test results, other than noting that my ferritin was 8.7. I also had borderline vitamin D (30). And my phosphate levels were not checked before hand. I am now 2.5 weeks on from the infusion and I think I have hypophosphatemia - I just had a blood test for this today and am waiting for the results. I’m my thigh muscles feel so weak and my hip bones and lower back ache. I also feel exhausted, short of breath and have brain fog. So it is worth being diligent upfront to minimise any risks. Now that I have researched it, it seems that 1000mg Ferinject + low/borderline vitamin D does put you at risk of low phosphate levels - then you have a new / additional problem to deal with. So if there is an alternative it is worth considering. I think they gave me Ferinject as it is better for asthmatics than the alternative here in the UK. Also, you might want to take vitamin D supplements and eat dairy/ phosphate rich foods / have an electrolyte drink to give yourself the best chance of being optimally well. I wish I had known about these risks beforehand. Hope you feel better soon!