- The presentation of hypopituitarism is diverse given that it can be related to a deficiency of any of the anterior pituitary hormones (ACTH, FSH/LH, GH, TSH, PRH).
- In hypopituitarism, the order of hormone loss is as follows: GH (first) –> LH/FSH –> TSH –> ACTH which according to Ken Feingold at the VA is in order of least important hormone to most important. It is the inverse of replacement of hormones in panhypopituitarism in that we replace cortisol via hydrocortisone first then FT4 via levothyroxine and so on.
- In these cases, our endocrine colleagues will be involved but important to note that you start with hydrocortisone replacement and do not start the patient on other hormone replacement until the adrenal function has stabilized as you can precipitate adrenal crisis.
- Typical replacement is hydrocortisone 15-25mg daily in divided or physiologic dosing (we typically see 10mg QAM and 5mg QPM to start).
- A note on hyponatremia/hyperkalemia in secondary adrenal insufficiency or ACTH deficiency
- Important to note that you do not see the salt wasting, volume contraction, and hyperkalemia that you see in primary adrenal insufficiency as secondary adrenal insufficiency does not affect the zona glomerulosa where aldosterone is made and thus does not result in aldosterone deficiency.
- As mentioned above, adrenal insufficiency may be the presenting symptom of panhypopituitarism or a separate clinical entity and attached is a diagram from the 2009 article in NEJM by Bornstein outlining a checklist for common predisposing factors for adrenal insufficiency.
Unintentional Weight Loss
- Defined as > 10% usual body weight loss over 6 months.
- It has been estimated that roughly 5-10% of outpatients over the age of 65 will present in the ambulatory setting for evaluation of unintentional weight loss.
- The differential is broad and the following article from AAFP on unintentional weight loss has a nice overview of an approach to unintentional weight loss in older adults.