Other labs in hyperthyroidism

Q; In patients with hyperthyroidism, serum total, low-density (LDL), and high-density lipoprotein (HDL) cholesterol tends to be? - select one

A) higher

B) lower

Answer: B

It is always interesting and a good clinical and academic exercise to look for nonspecific laboratory findings in patients with hyperthyroidism. These patients usually have

• lower total, LDL, and HDL cholesterol (due to high sympathathetic activity)
• increased red blood cell (RBC) mass*
• increased plasma volume*
• higher alkaline phosphatase level^
• higher osteocalcin concentrations^

*RBC mass is increased, but the plasma volume is even more increased, showing up as a normochromic, normocytic anemia

^ due to increased bone turnover

#endocrinology

#laboratory-medicine

References: 

1. O'Brien T, Katz K, Hodge D, et al. The effect of the treatment of hypothyroidism and hyperthyroidism on plasma lipids and apolipoproteins AI, AII and E. Clin Endocrinol (Oxf) 1997; 46:17.

2. Dorgalaleh A, Mahmoodi M, Varmaghani B, Kiani Node F, Saeeidi Kia O, Alizadeh Sh, Tabibian Sh, Bamedi T, Momeni M, Abbasian S, Kashani Khatib Z. Effect of thyroid dysfunctions on blood cell count and red blood cell indice. Iran J Ped Hematol Oncol. 2013;3(2):73-7. Epub 2013 Apr 22. PMID: 24575274; PMCID: PMC3915449.

3. Kumeda Y, Inaba M, Tahara H, Kurioka Y, Ishikawa T, Morii H, Nishizawa Y. Persistent increase in bone turnover in Graves' patients with subclinical hyperthyroidism. J Clin Endocrinol Metab. 2000 Nov;85(11):4157-61. doi: 10.1210/jcem.85.11.6979. PMID: 11095447.