• Jacinta King

Blood Testing Post Surgery



As discussed in my post about supplementation requirements post surgery, it is very common to develop vitamin and mineral deficiencies after weight loss surgery.


Vitamin and mineral deficiencies occur because:


  1. Even though you may have great diet quality, you simply cannot eat the same quantity of food that you used to in order to meet the required amounts of vitamin and minerals that you need.

  2. The way vitamins and minerals are processed in the body has now been forever changed. Many nutrients are no longer absorbed as well.


Research has shown the following rates of deficiencies in post weight loss surgery patients (just to name a few):


  • Iron deficiency in up to 55% of bypass patients and 18% of sleeve patients

  • Vitamin B12 deficiency in up to 20% of bypass and sleeve patients

  • Vitamin D deficiency in up to 100% of bypass and sleeve patients

  • Zinc deficiency in up to 40% of bypass patients and 19% of sleeve patients

  • Vitamin A deficiency in up to 70% of bypass patients

  • Folate deficiency in up to 65% of bypass and sleeve patients


(Source: American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients)

Your vitamin and mineral levels can be tested through a blood test. With such high prevalence rates of deficiencies it is very important your levels are tested and supplementation prescribed accordingly in order to avoid outcomes such as anaemia, osteoporosis and poor eyesight, which can all result from untreated deficiencies.


How regular do I test?

Generally speaking it is recommended that your bloods are checked pre surgery and then again at 3, 6 and 12 months post surgery, moving to 6 monthly until stable and then annually long term. More regular testing will be required to monitor diagnosed deficiencies. Your healthcare practitioner can further guide you on how regular you need to test.


Remember: some deficiencies become more prevalent 2, 3, and even 5 years down the track. This is why it is important to not get complacent after a few good blood test results immediately after surgery - this doesn't mean you're in the clear! You still need to take your supplements and have your levels routinely checked long term.


What needs to be tested?

This is a summary of the key nutrients which should be routinely tested:


  • Full Blood Count

  • Electrolytes & Liver Function Tests

  • Iron Studies

  • Vitamin B12

  • Folate

  • Homocysteine

  • Vitamin A

  • Vitamin D

  • Parathyroid Hormone

  • Calcium

  • Zinc

  • Magnesium


Depending on your situation, surgery and symptoms, your Dietitian/Surgeon/GP may recommend adding on other tests such as Thiamin, Vitamin K, Vitamin E and Copper. Your healthcare practitioner can further guide you on this.


- Jacinta


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