Author
Hormone deficiency (%)
N
Ayuk et al. (2004)
Cortisol
72/87a
33
Thyroid
60/72
Gonadotrophin
67/83
Bills et al. (1993)
Cortisol
82
33
Thyroid
89
Gonadotrophin
64
ADH
11
Da Motta et al. (1999)
Cortisol
50
16
Thyroid
55
Gonadotrophin
55
Dubuisson et al. (2007)
Cortisol
80
24
Thyroid
70
Gonadotrophin
40
Growth hormone
15
ADH
0
Gruber et al. (2006)
Cortisol
72
36
Thyroid
48
Gonadotrophin
18
ADH
7
Lubina et al. (2005)
Cortisol
40
40
Thyroid
54
Gonadotrophin
79
ADH
8
Randeva et al. (1999)
Cortisol
58
35
Thyroid
45
Gonadotrophin
45
ADH
6
Sibal et al. (2004)
Cortisol
60
45
Thyroid
57
Semple et al. (2005)
Cortisol
61
62
Thyroid
70
Gonadotrophin
40
Growth hormone
6
The most important hormone deficiency is that of adrenocorticotrophic hormone (ACTH) and subsequently cortisol, which is one of the major causes of mortality in pituitary apoplexy (Lee et al. 2008). The percentage of patients reported with hypocortisolaemia following apoplexy varies from 50 to 83 % (da Motta et al. 1999; Randeva et al. 1999; Sibal et al. 2004; Semple et al. 2005; Kerr and Wierman 2011; Rajasekaran et al. 2011; Renabir and Baruah 2011). The possible reason for the variation in the reported incidence of cortisol deficiency may be different definitions of hypocortisolaemia as well as varying assays for the ACTH. The deficiency in ACTH may result in non-specific symptoms of shock and rapid deterioration of the patient’s condition, which may be fatal if left untreated (Mattke et al. 2002). In the severely stressed patient with pituitary apoplexy, the cortisol levels may fail to respond to adequate levels, due to a relative deficiency of ACTH. Dilutional hyponatraemia results from vasopressin release from the posterior pituitary, which has an inhibitory effect on water secretion (Renabir and Baruah 2011). A low cortisol also results in impaired vasoconstriction and haemodynamic instability.
Gonadotrophins were low in 75–85 % of patients. Hypothyroidism was reported in 42–55 % of patients, while thyroid-stimulating hormone (TSH) was documented as being low in 50–55.5 %. Growth hormone has been reported to be low in up to 88 % of patients (Cardoso and Peterson 1984; Randeva et al. 1999; da Motta et al. 1999; Sibal et al. 2004; Semple et al. 2005; Dubuisson et al. 2007; Renabir and Baruah 2011). Low prolactin levels have been associated with high intrasellar pressures and severe pituitary apoplexy (Rajasekaran et al. 2011). Severe ischaemic necrosis may give rise to low serum prolactin levels, whereas those individuals who have normal or elevated serum prolactin levels tend to have less severe hypopituitarism. In patients with functional tumours, remission of Cushing’s disease and acromegaly has been reported following pituitary apoplexy (Dunn et al. 1975; Tamasawa et al. 1988; Kamiya et al. 2000; Fraser et al. 2009; Choudhry et al. 2011).
Long-term hormone replacement will be required in up to 80 % of patients with pituitary apoplexy. Dubuisson et al. (2007) reported that the majority of their series required replacement: adrenal 80 %, thyroid 70 %, gonadal 40 % and growth hormone 15 %. In general, long-term follow-up of patients with pituitary apoplexy replacement requirements will be corticosteroids in 40–85 %, thyroid hormone in 50–70 %, sex hormones in 40–80 % and growth hormone in 16 % of cases (Renabir et al. 2011). Some authors have suggested that early surgery may lead to better restoration or preservation of pituitary function, while others have not reported any difference between surgically and conservatively managed patients. Marouf and colleagues (2010) in their surgical series reported only 27 % of patients having normal pituitary function following apoplexy, while 42 % had panhypopituitarism, 31 % corticotrophic hypopituitarism. They also found that residual pituitary gland seen on MRI on follow-up did not correlate with pituitary function (Marouf et al. 2010). Leyer et al. (2011) reported no significant difference in endocrine outcome after 21 months of follow-up between patients operated on and treated conservatively. Sibal et al. (2004) in their reported series found similar endocrine outcomes at follow-up between the surgically treated and conservatively managed patients. Ayuk and co-workers (2004) reported no difference in their series in cortisol and thyroid replacement in patients managed with surgery or conservatively.
The incidence of diabetes insipidus (DI) varies between 0 and 27 % of cases (Mauerhoff et al. 1991; Bills et al. 1993; Sweeney et al. 2004; Gruber et al. 2006; Dubuisson et al. 2007; Marouf et al. 2010; Renabir and Baruah 2011). DI may be a presenting feature of the pituitary apoplexy or it may occur postoperatively. Preoperative DI is rarely seen and in some series has not been reported at all (Duboisson et al. 2006). This may be attributable to the preservation of the posterior pituitary as a result of its different blood supply from the inferior hypophyseal artery rather than the superior hypophyseal artery that supplies the anterior pituitary and usually the tumour (Bills et al. 1993, Reid et al. 1985). However, postoperative DI appears to be more common and is described in 16 % of patients (Randeva et al. 1999; Rajasekaran et al. 2011). Postoperative DI is due to a lack of antidiuretic hormone (ADH) due to surgical manipulation of the neurohypophysis (Kristof et al. 2009). DI presents in the first two postoperative days in 86 % of cases and is transient in the majority of cases with half resolving in the first week (Bills et al. 1993; Kristof et al. 2009; Grant et al. 2012). Gruber et al. (2006) reported DI in 20 % who underwent surgery, compared to 0 % who was treated conservatively. On long-term follow-up ADH replacement therapy has been reported in 6–25 % of patients (Bills et al. 1993; Rajasekaran et al. 2011; Renabir and Baruah 2011).
Hyponatraemia following pituitary apoplexy has been described in up to 40 % of patients (Randeva et al. 1999). Hyponatraemia can occur as an early or late event, and it can be isolated. Alternatively, it can occur in the second phase of the triple response when there is ADH release (Grant et al. 2012). Hyponatraemia in the early phase of pituitary apoplexy may result from hypocortisolaemia and secondary activation of ADH, which has an inhibitory effect on water secretion (Diederich et al. 2003; Lee et al. 2008; Rajasekaran et al. 2011). Hyponatraemia may also result from surgery for the apoplexy (Kelly et al. 1995; Taylor et al. 1995). The syndrome of inappropriate antidiuretic hormone secretion (SIADH) rarely occurs in pituitary apoplexy except for a few case reports. SIADH may occur due to sparing of the neurohypophysis leading to hyponatraemia (Agrawal and Mahapatra 2003). Surgical removal of the apoplectic pituitary adenoma may distort the hypophyseal stalk resulting in a surge of antidiuretic hormone release ultimately resulting in fluid overload and dilutional hyponatraemia (Lee et al. 2008). It remains unknown whether cerebral salt wasting occurs in the setting of pituitary apoplexy.
13.3 Emergency Management
Awareness that ACTH deficiency leads to inadequate cortisol concentrations, particularly with acute coexistent stress is critical. Partial or complete hypopituitarism confers the morbidity and mortality associated with this condition (Laws et al 2008, Turgut et al. 2010). In the individual in whom apoplexy is suspected, it is critical to draw blood for electrolytes, glucose, cortisol, liver functions, renal function, clotting screen, full blood count, prolactin, TSH, free T4, insulin-like growth factor-1 (IGF-1), growth hormone, luteinising hormone (LH), follicle-stimulating hormone (FSH) and testosterone in men and oestradiol in women (Rajasekaran et al. 2011). As pituitary apoplexy is a life-threatening condition it warrants careful attention to fluid management, and in some instances, blood transfusions are required. Administration of hydrocortisone will have a dual effect of replacing endogenous cortisol deficiency, and to some degree to relieve oedema of the parasellar structures (Murad-Kejbou and Eggenberger 2009). The most notable improvement following glucocorticoid administration is the reduction of haemodynamic instability. Varying dosing regimens of hydrocortisone have been recommended in the setting of acute pituitary apoplexy, but there is insufficient evidence to recommend one versus another. Some sources recommend a dose of 50 mg intravenously every 6 h (Chanson et al. 2004; Nawar et al. 2008). Other centres recommend a bolus dose of between 100 and 200 mg of intravenous hydrocortisone, followed by 50–100 mg six hourly by intramuscular injection (Vanderpump et al. 2011). Hydrocortisone administered either intravenously or intramuscularly is favoured over dexamethasone (Vanderpump et al. 2011). One small study reports an increased mortality with dexamethasone use, but these findings have not been consistently found in other studies (da Motta et al. 1999). A deficiency of glucocorticoids can contribute to haemodynamic instability through its action on raising antidiuretic hormone and fluid retention as well as impaired vasoconstriction. There is concern that intermittent administration of intermittent intravenous hydrocortisone may result in rapid saturation of cortisol binding globulin, with resultant enhanced filtration in the urine and consequently continuous infusions of hydrocortisone is sometimes advised (Rajasekaran et al. 2011).
A random serum cortisol of greater than 550 nmol/L indicates that hydrocortisone may be withheld. Nevertheless, one should never delay administration of hydrocortisone, pending the serum cortisol results. Hyponatraemia is a frequent complication, occurring in up to 40 % of pituitary apoplexy (Randeva et al. 1999). The cause should be sought and it should be corrected as far as is possible prior to surgery (Chuang et al. 2006). The usual precipitants are those of hypocortisolaemia and syndrome of inappropriate antidiuretic hormone (SIADH). Hypothyroidism is not a contraindication to surgery unless it is severe, and the primary clinician should inform the anaesthetist in order to avoid central nervous system suppressants.
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